id stringlengths 2 7 | question stringlengths 12 1.71k | answer stringlengths 1 1.1k | answer_type stringclasses 11 values | category stringclasses 1 value | difficulty stringclasses 3 values | __index_level_0__ int64 7 229k |
|---|---|---|---|---|---|---|
486702 | What is the shorthand electron configuration of xenon? | [Kr] 5s^2 4d^10 5p^6 | String | Biology & Chemistry | Senior High School | 75,021 |
1735716 | Calculate {eq}\displaystyle
K_c
{/eq} for the following reaction: {eq}\displaystyle
2 SO_2(g) + O_2(g) \leftrightarrow 2 SO_3(g)
{/eq}
{eq}\displaystyle
K_p = 35.93 \ at \ 76^\circ C
{/eq}. Give your answer to 3 significant figures. | 1.03e3 | Float | Biology & Chemistry | Senior High School | 162,136 |
672109 | Helper T-cells are required for all except:
a. Antibody-mediated immunity.
b. Inflammation.
c. Cell-mediated immunity.
d. Activation of specific lymphocytes to produce a clone of effector cells. | b | Multiple Choice | Biology & Chemistry | University | 59,245 |
821327 | The following reaction was performed in a sealed vessel at 744 degrees C:
{eq}H_2(g) + I_2(g) \rightarrow 2HI(g)
{/eq}
Initially, only {eq}H_2
{/eq} and {eq}I_2
{/eq} were present at concentrations of {eq}[H_2]
{/eq} = 3.70M and {eq}[I_2]
{/eq} = 2.70M. The equilibrium concentration of {eq}I_2
{/eq} is 0.0500 M. What is the equilibrium constant, {eq}K_c
{/eq}, for the reaction at this temperature? | 535.05 | Float | Biology & Chemistry | Senior High School | 136,051 |
1767936 | A rigid sealed #"3.70 L"# vessel contains #"0.12 mol"# of #He(g)# and #"0.24 mol"# #Ne(g)# at #25^@ "C"#. What is the total pressure in the vessel? | 2.38 atm | Float | Biology & Chemistry | Senior High School | 35,450 |
1511561 | A chromosome consists of
A) 60% DNA and 40% protein.
B) 60% protein and 40% DNA.
C) 20% protein and 80% DNA.
D) 80% protein and 20% DNA.
E) 50% DNA and 50% protein. | B | Multiple Choice | Biology & Chemistry | Senior High School | 63,949 |
1311441 | What is the mole-mole ratio (conversion factor) for {eq}CaI_2
{/eq} (calcium iodide) to {eq}Ca_3(PO_4)_2
{/eq} (calcium phosphate) in the following reaction?
{eq}3CaI_2(aq) + 2(NH_4)_3PO_4(aq) \to Ca_3(PO_4)_2(s) + 6NH_4I(aq)
{/eq} | 3:1 | Integer | Biology & Chemistry | Senior High School | 210,879 |
455808 | Homologous chromosomes separate during | anaphase I of meiosis I | Multiple Choice | Biology & Chemistry | Senior High School | 199,233 |
1538856 | Initially, there are 33 moles of A and 0 moles of B. How many moles of A and B will be present after the system reaches equilibrium?
a) 33 moles A; 0 moles B.
b) 0 moles A; 33 moles B.
c) 3 moles A; 30 moles B.
d) Equal amounts of A and B. | d | Multiple Choice | Biology & Chemistry | Senior High School | 142,372 |
105473 | What is the {eq}\displaystyle \rm rms
{/eq} speed of {eq}\displaystyle \rm Cl_2
{/eq} molecules at {eq}\displaystyle \rm 435 \ K
{/eq}? | 391 m/s | Integer | Biology & Chemistry | Senior High School | 160,389 |
186434 | A 5.17 g sample of neon gas has a volume of 882 mL at a pressure of 2.15 atm. What is the temperature of the Ne gas sample in degrees Celsius? | -182.9 degrees Celsius | Float | Biology & Chemistry | Senior High School | 50,919 |
187495 | If a male was under a lot of stress (elevated SNS activity), which of the following statements would be true given what is known about the regulation of the male sexual response?
A. It would be easier for them to achieve and maintain an erection.
B. They would reach the ejaculation stage more rapidly.
C. It would be more difficult for them to achieve and maintain an erection.
D. They would take longer to reach the ejaculation phase.
E. Both A and B.
F. Both B and C. | F | Multiple Choice | Biology & Chemistry | University | 164,082 |
1071615 | When {eq}6.25 \ grams
{/eq} of pure iron are allowed to react with oxygen, a black oxide forms. If the products weighs {eq}8.15 \ g
{/eq}, what is empirical formula of the oxide? | FeO | String | Biology & Chemistry | Senior High School | 116,874 |
2061328 | Calculate the pH of a 0.105 M {eq}HNO_2
{/eq} solution. | 2.16 | Float | Biology & Chemistry | Senior High School | 93,377 |
1542731 | Is infertility part of Darwin's natural selection? | Yes | Boolean | Biology & Chemistry | Senior High School | 1,008 |
1061004 | Write the complete balanced equation for the decomposition of water ({eq}H_2O
{/eq}). | 2H2O(l) -> 2H2(g) + O2(g) | Expression | Biology & Chemistry | Senior High School | 186,681 |
327693 | Do gamma delta T-cells recognize CD1? | Yes | Boolean | Biology & Chemistry | University | 110,578 |
355314 | After 67.0 minutes, 32.0{eq}\%
{/eq} of a compound has decomposed. What is the half-life of this reaction assuming first order kinetics? | 120.42 min | Float | Biology & Chemistry | Senior High School | 179,964 |
759010 | The half-life of radium is 1690 years. If 90 grams are present now, how much will be present in 760 years? | 65.90 g | Float | Biology & Chemistry | Senior High School | 62,942 |
1618019 | Which of the following has more moles?
1) 4 grams of {eq}\rm
H_2
{/eq}.
2) 16 grams of {eq}\rm
O_2
{/eq}.
3) 32 grams of {eq}\rm
S
{/eq}.
4) 24 grams of {eq}\rm
CH_4
{/eq}. | A | Multiple Choice | Biology & Chemistry | Senior High School | 141,711 |
695632 | A {eq}50.0 \ mL
{/eq} sample of {eq}1.56 \times 10^{-2} \ M \ Na_2SO_4(aq)
{/eq} is added to {eq}50.0 \ mL
{/eq} of {eq}1.22 \times 10^{-2} \ M \ Ca(NO_3)_2(aq).
{/eq} What percentage of the {eq}Ca^{2+}
{/eq} remains unprecipitated? | 0% | Percentage | Biology & Chemistry | Senior High School | 70,746 |
792588 | The manufacture of aluminum includes the production of cryolite (Na_3AlF_6) from the following reaction:
6HF + 3NaAlO_2 -->Na_3AlF_6 +3H_2O + Al_2O_3
How much NaAlO_2 (sodium aluminate) is required to produce 4.80 kg of Na_3AlF_6?
........kg | 5.6215 kg | Float | Biology & Chemistry | Senior High School | 78,781 |
262430 | Use the tabulated electrode potentials to calculate K for the oxidation of iron by H{eq}^+{/eq} (at 25°C):
{eq}\rm 2 Fe(s) + 6H^+ (aq) \to 2Fe^{3+}(aq) + 3H_2(g)
{/eq} | 1.14e4 | Float | Biology & Chemistry | University | 108,904 |
909615 | How many moles are in {eq}4.40 \times 10^{25}
{/eq} molecules of {eq}O_3
{/eq}? | 73.1 moles
O_3 | Float | Biology & Chemistry | Senior High School | 25,674 |
113145 | How do you prepare a 750 mL stock solution with a 0.40 M {eq}Na_2S_2O_3
{/eq}? | 47 g Na2S2O3 | Other | Biology & Chemistry | Senior High School | 32,313 |
1417226 | Complete and balance the following acid/base neutralization reaction.
{eq}HNO_3(aq) + Mg(OH)_2(aq) \to
{/eq} | 2HNO3(aq) + Mg(OH)2(aq) -> Mg(NO3)2(aq) + 2H2O(l) | Expression | Biology & Chemistry | Senior High School | 93,767 |
812675 | The weak acid HZ has a {eq}K_a
{/eq} of {eq}2.55 \times 10^{-4}
{/eq}. Calculate the pOH of a 0.0300 M HZ solution. | 11.44 | Float | Biology & Chemistry | Senior High School | 70,438 |
1053557 | Which of these processes happens during the PR interval:
1) Beginning of ventricular filling
2) End of ventricular filling
3) Atrial relaxation
4) Atrial filling | A | Multiple Choice | Biology & Chemistry | University | 196,338 |
2108268 | Consider the following reaction.
{eq}A(aq) \leftrightharpoons 3B(aq); K_c = 2.49 \times 10^{-6}
{/eq} at 500 K
If a 5.40 M sample of {eq}A
{/eq} is heated to 500 K, what is the concentration of {eq}B
{/eq} at equilibrium? | 0.0238 M | Float | Biology & Chemistry | Senior High School | 183,740 |
1662138 | Calculate the hydroxide ion concentration in an aqueous solution with a pOH of 2.34 at 25 degrees Celsius. | 0.00457 M | Float | Biology & Chemistry | Senior High School | 176,460 |
750032 | What is the net ionic equation for the reaction of excess CuSO_4 with NH_3? | Cu^(2+)(aq) + 4NH_3(aq) -> [Cu(NH_3)_4]^(2+)(aq) | Expression | Biology & Chemistry | Senior High School | 123,312 |
351505 | What would likely occur if #"potassium iodide"# were added to #"ferric nitrate"#? | Fe(NO_3)_3(aq) + 3KI(aq) rightleftharpoons3K(NO_3)(aq) + FeI_3(aq) | Expression | Biology & Chemistry | Senior High School | 22,696 |
1992392 | Consider a solution of a weak acid at a pH equal to its pKa.
By how much would the pH change, and in which direction, if we added to this solution enough base to neutralize 10% of the total acid? | 0.09 | Float | Biology & Chemistry | University | 148,744 |
1456538 | A sample of gas has a mass of 0.555 g. Its volume is 119 mL at a temperature of 86ºC and pressure of 746 mmHg. Find the molar mass of the gas. | 13.87 g/mol | Float | Biology & Chemistry | Senior High School | 105,017 |
1332175 | How many CHARGED nuclear, and electronic particles are present in #"potassium nitride"#? | 64 protons and 64 electrons | Integer | Biology & Chemistry | Senior High School | 35,008 |
1613870 | What is the pH of a solution that results from adding 0.059 mol Sr(OH)2 (s) to 1.57 L of a buffer comprised of 0.21 M HF and 0.21 M NaF? | 3.43 | Float | Biology & Chemistry | University | 136,271 |
300452 | The following measurements were made to determine the density of a material whose value was, according to the handbook of Chemistry and Physics, 1.16 g/mL. What can be said about these measurements?
Trial 1 is 0.95 g/mL, Trial 2 is 1.16 g/mL, Trial 3 is 1.26 g/mL
A. They are accurate but not precise.
B. They are neither accurate nor precise. | B | Multiple Choice | Biology & Chemistry | Senior High School | 145,350 |
2001758 | Balance this equation:
{eq}Ca_3(PO_4)_2(aq) + HCl(aq) \to CaCl_2(aq) + H_3PO_4(aq)
{/eq} | $Ca_3(PO_4)_2(aq) + 6HCl(aq) \to 3CaCl_2(aq) + 2H_3PO_4(aq)$ | Expression | Biology & Chemistry | Senior High School | 149,518 |
435833 | Is animal photosynthesis possible? | yes | Boolean | Biology & Chemistry | Senior High School | 53,889 |
1149735 | Which is a product of the Krebs Cycle? | carbon dioxide, NADH, FADH2, and ATP or GTP | List | Biology & Chemistry | Senior High School | 34,903 |
742851 | When a solution of potassium iodide is mixed with a solution of lead nitrate, a bright yellow solid precipitate forms. Calculate the mass of the solid produced (molar mass = 461 g/mol) when starting with a solution containing 206.70 g of potassium iodide (molar mass = 166 g/mol), assuming that the reaction goes to completion.
{eq}2KI(aq) + Pb(NO_3)_2(aq) \to PbI_2(s) + 2KNO_3(l)
{/eq} | 287.01 g | Float | Biology & Chemistry | Senior High School | 82,152 |
381647 | At 45 {eq}^o
{/eq}C, K{eq}_c
{/eq} = 0.00991 for the reaction below.
H{eq}_2
{/eq} + Cl{eq}_2
{/eq} {eq}\to
{/eq} 2HCl
In an experiment carried out at 45 {eq}^o
{/eq}C, the initial concentrations were |H{eq}_2
{/eq}| = |Cl{eq}_2
{/eq}| = |HCl| = 0.750 mol/L. What is the equilibrium concentration of HCl? Give your answer in mol/L, accurate to three significant figures. | 0.107 mol/L | Float | Biology & Chemistry | Senior High School | 153,226 |
29417 | What is the total amount of ATP produced by cellular respiration? | Up to 38 ATP | Integer | Biology & Chemistry | Senior High School | 39,635 |
1705221 | Identify the acid-base conjugate pairs in the following reaction.
{eq}NH_4^+(aq) + HCO_3^-(aq) \leftrightharpoons NH_3(aq) + H_2CO_3(aq)
{/eq} | The acid-conjugate base pair is NH4+(aq)-NH3(aq).
The base-conjugate acid pair is HCO3-(aq)-H2CO3(aq). | List | Biology & Chemistry | Senior High School | 208,808 |
221133 | Calculate the Ksp Ca(OH){eq}_2
{/eq} if 25 cm{eq}^3
{/eq} of a saturated solution required 11.45 cm{eq}^3
{/eq} of 0.1 mol/dm{eq}^3
{/eq} HCl for neutralization. | 4.3e-5 | Float | Biology & Chemistry | Senior High School | 130,167 |
503241 | For the reaction {eq}N_2 O_4(g) 2NO_2(g), K_p = 0.25
{/eq}at a certain temperature. Calculate the equilibrium pressures of {eq}NO_2 (g)
{/eq} and {eq}N_2 O_4 (g)
{/eq}if the initial pressure(s) of the components when placed in an otherwise empty container are as follows: Initial {eq}P_NO2 = 0.50 atm
{/eq} Initial {eq}P_N2O4 = 0.50 atm
{/eq} | P_N2O4 = 0.5625 atm, P_NO2 = 0.375 atm | Float | Biology & Chemistry | Senior High School | 121,607 |
1140895 | Which of the following represents 1.5 moles of diborane gas, {eq}B_{2}H_{6}
{/eq} ?
(a) 33.6 L diborane gas at STP
(b) 27.68 g diborane gas
(c) {eq}6.02\times 10^{23}
{/eq} diborane gas molecules
(d) all of the above
(e) none of the above | D | Multiple Choice | Biology & Chemistry | Senior High School | 190,215 |
821295 | The pH of 0.50 M HBrO (aq) is 4.50. Calculate the change in pH when 6.50 g of sodium hypobromite is added to 110. mL of the solution. | 4.15 | Float | Biology & Chemistry | University | 75,045 |
989468 | Which of the following would dissolve in water?
(a) {eq}CCl_4
{/eq}
(b) {eq}LiCl
{/eq}
(c) {eq}CH_4
{/eq}
(d) {eq}PCl_6
{/eq}. | b | Multiple Choice | Biology & Chemistry | Senior High School | 165,716 |
645213 | The best understood bacterial cytoskeleton are composed primarily of what? | FtsZ and MreB | List | Biology & Chemistry | University | 143,107 |
1239992 | How many molecules are in 92.0 grams of {eq}N_2O
{/eq}? | 9.23e+23 molecules | Float | Biology & Chemistry | Senior High School | 36,742 |
2078135 | How do you determine pH from pKa? | For buffer solutions: pH = pKa + log(([A^(-)])/([HA])). For strong acids: pH = -log([HA]). For weak acids: use the ICE table method to determine [H^(+)] and then use pH = -log([H^(+)]). | List | Biology & Chemistry | Senior High School | 96,215 |
1303327 | What is {eq}[H_3O^+]
{/eq} in a solution obtained by dissolving 215 mL {eq}HCl(g)
{/eq}, measured at 23 degrees C and 757 mmHg, in 4.30 L of aqueous solution? | 0.00205 M | Float | Biology & Chemistry | Senior High School | 87,215 |
203084 | Find the percent dissociation of a 0.120 M solution of a weak monoprotic acid with {eq}K_a = 2.0 \times 10^{-5}
{/eq}. | 1.28% | Percentage | Biology & Chemistry | Senior High School | 74,935 |
1681251 | How you would prepare 500mL of a PIPES buffer at pH 7 which the concentration of weak base is 0.2M? You have available PIPES (MM= 302.37 g/mol, pka= 6.76) and sodium hydroxide (MM= 40.00 g/mol). | 47.62 g of PIPES and 4 g of NaOH | List | Biology & Chemistry | University | 79,263 |
165170 | How many mL of a 0.101 M NaOH solution are required to neutralize 25.0 mL of a 0.119 M HCl solution?
HCI + NaOH --> NaCl + H_2O | 29 mL | Float | Biology & Chemistry | Senior High School | 223,681 |
1442879 | Consider the statement, "mitosis separates sister chromatids, but meiosis separates homologous chromosomes." Is this a valid statement? Why or why not? | Yes | Boolean | Biology & Chemistry | Senior High School | 95,643 |
1240079 | Consider the following reaction: {eq}A \ + \ B \ + \ C \ \rightarrow \ D
{/eq}
The rate law for this reaction is as follows: {eq}Rate=k [A] [C]^2 [B]^{1/2}
{/eq}
Suppose the rate of the reaction at certain initial concentrations of A, B, and C is {eq}1.11*10^{-2} M/s
{/eq}. What is the rate of the reaction if the concentrations of A and C are doubled and the concentration of B is tripled? | 0.154 M/s | Float | Biology & Chemistry | Senior High School | 6,667 |
679489 | Which portion of the cerebral cortex is most directly involved in making plans and formulating moral judgments? | Frontal Lobes | String | Biology & Chemistry | Senior High School | 176,272 |
826029 | How do you calculate the dissociation constant in chemistry? | K = [A+][B-]/[AB] | Expression | Biology & Chemistry | Senior High School | 39,980 |
404644 | How many grams of hydrochloric acid should we use so we have exactly enough to react with 40g of sodium hydroxide? Write a chemical reaction, balance it, and then perform the calculation. | 36 g | Integer | Biology & Chemistry | Senior High School | 201,844 |
1735464 | Consider the insoluble compound zinc cyanide , Zn(CN)2 . The zinc ion also forms a complex with ammonia . Write a balanced net ionic equation to show why the solubility of Zn(CN)2 (s) increases in the presence of ammonia and calculate the equilibrium constant for this reaction. For Zn(NH3)42+ , Kf = 2.9 109 Find K | 2.32e-2 | Float | Biology & Chemistry | University | 205,079 |
1894657 | How many moles of oxygen are in 115 grams of {eq}Fe_2(CO_3)_3
{/eq}? | 3.55 moles | Float | Biology & Chemistry | Senior High School | 126,887 |
1934279 | What are the two key structures necessary for the process of translation to occur? | ribosome and mRNA | List | Biology & Chemistry | Senior High School | 76,664 |
1223220 | What amount of HCl gas must be added to 1.00 L of a buffer solution that contains acetic acid of 2.0M and acetate of 1.0M in order to produce a solution with a ph of 3.85? | 0.665 moles or 24.2 grams | Float | Biology & Chemistry | University | 154,474 |
527267 | What is the half-life in minutes of a compound if 75.0% of a given sample decomposes in 85.0 minutes? Assume first-order kinetics. | 43.312 min | Float | Biology & Chemistry | Senior High School | 27,986 |
324419 | A combustion analysis of a 0.503 g sample of an unknown hydrocarbon yields 1.53 g CO{eq}_2
{/eq} and 0.756 g H{eq}_2
{/eq}O. What is the empirical formula of the sample? | C5H12 | String | Biology & Chemistry | Senior High School | 18,706 |
498976 | The correct IUPAC name for 2-isopropylbutane is: a) 2-ethylpentane b) 2,3-dimethylpentane c) 2-methylhexane d) 3-methylhexane | d | Multiple Choice | Biology & Chemistry | Senior High School | 15,364 |
507404 | Would you expect an organic compound to be soluble in water? | Yes, if they have polar functional groups like hydroxyl or carbonyl | Boolean | Biology & Chemistry | Senior High School | 48,724 |
319892 | How many grams of N{eq}_2{/eq}O are in a 230 mL sample if the pressure is 201,532 Pa at -5.31 degrees Celsius? | 0.915 g | Float | Biology & Chemistry | Senior High School | 16,304 |
736312 | Which electron dot diagram shows the bonding between 2 chlorine atoms? | :Cl:::Cl: | Multiple Choice | Biology & Chemistry | Senior High School | 220,631 |
1146037 | At a particular temperature, {eq}\displaystyle \rm K=6.0 \times 10^{-6}
{/eq} for the reaction {eq}\displaystyle \rm 2CO_2 (g) \rightleftharpoons 2CO (g) + O_2 (g)
{/eq}. If {eq}\displaystyle \rm 3.0 \ moles
{/eq} of {eq}\displaystyle \rm CO_2
{/eq} is initially placed into a {eq}\displaystyle \rm 5.0 \ L
{/eq} vessel, calculate the equilibrium concentration for {eq}\displaystyle \rm CO
{/eq}. | 0.016 M | Float | Biology & Chemistry | Senior High School | 189,170 |
797129 | A {eq}0.8612\ g
{/eq} sample of a mixture consisting of {eq}\rm NaBr,\ NaI\ and\ NaNO_3
{/eq} was analysed by adding {eq}\rm AgNO_3
{/eq} to precipitate the {eq}\rm Br^-
{/eq} and {eq}\rm I^-
{/eq}, yielding {eq}1.0186\ g
{/eq} mixture of {eq}\rm AgBr
{/eq} and {eq}\rm AgI
{/eq}. The precipitate was then heated in a stream of {eq}\rm Cl_2
{/eq}, converting it to {eq}0.7125\ g
{/eq} of {eq}\rm AgCl
{/eq}. Calculate the {eq}\rm \%w/w\ NaNO_3
{/eq} in the sample. | 30.72% | Percentage | Biology & Chemistry | University | 207,161 |
528270 | 17.8 g of chlorine were used and yielded 43.5g of chlorine dioxide. Calculate the theoretical yield in grams of chlorine dioxide. | 33.8 g | Float | Biology & Chemistry | Senior High School | 148,047 |
484517 | What sequence of nucleotide pairs in a Drosophila gene will encode the amino acid sequence met-trp-phe-trp-met (reading from the amino terminus to the carboxyl terminus)? | ATGTGGTTCTGGATG
TACTCCAAGACCTAC | String | Biology & Chemistry | Senior High School | 142,967 |
1051640 | Could an organism be both MR and VP positive? | yes | Boolean | Biology & Chemistry | University | 108,164 |
906768 | Draw the structure corresponding to the following IUPAC name.
trans-3-chlorocycloheptanol | /cimages/multimages/16/transs6794762621357100412.jpg | Other | Biology & Chemistry | Senior High School | 50,815 |
1464515 | The balanced equation for the combustion of ethanol (ethyl alcohol) is:
{eq}\displaystyle
C_2H_5OH(l) + 3O_2(g) \to 2CO_2(g) + 3H_2O(g)
{/eq}
How many {eq}\displaystyle
g
{/eq} of {eq}\displaystyle
CO_2
{/eq} will be produced by the combustion of {eq}\displaystyle
2
{/eq} mole of ethanol?
{eq}\displaystyle
\boxed{\space} \text{ g } CO_2.
{/eq} | 176 g | Integer | Biology & Chemistry | Senior High School | 227,587 |
1613983 | How many electrons are in O2-? | 10 | Integer | Biology & Chemistry | Senior High School | 7,456 |
1532439 | An organism is described as {eq}\displaystyle 2 n = 26
{/eq}. How many chromatids per chromosome are in one meiotic cell during Telophase 1? | 2 | Integer | Biology & Chemistry | Senior High School | 212,127 |
711342 | Draw the Lewis dot structure for the {eq}K^+
{/eq} ion. | K+ | String | Biology & Chemistry | Senior High School | 139,026 |
1682963 | Consider the following reaction.
P(NMe2 )3 (aq) + HCl(aq) {eq}\rightarrow
{/eq} PCl(NMe2 )2 (aq) + NHMe2 (aq); Keq = 16
The initial concentrations are {eq}[P(NMe2 )3 ] = 0.1 M, [HCl] = 0.1 M, [PCl(NMe2 )2 ] = 0.2 M
{/eq}, and {eq}[NHMe2 ] = 0.2 M
{/eq}? What will be the equilibrium concentration of {eq}[P(NMe2 )3 ]
{/eq}? | 0.06 M | Float | Biology & Chemistry | Senior High School | 136,604 |
905428 | How would you determine the Lewis structure for #CO#? | #"^(+):O-=C:^(-)# OR #:ddotO=C:# | Other | Biology & Chemistry | Senior High School | 69,637 |
127285 | If 80g {eq}KNO_3
{/eq} is mixed with 100g water at 30 degrees C how much will not dissolve? | 34.2 g | Float | Biology & Chemistry | Senior High School | 101,663 |
3836 | Write the expression for the equilibrium for the following generic chemical equation.
{eq}\displaystyle \rm CH_4 (g) + 2H_2S (g) \rightleftharpoons CS_2 (g) + 4H_2 (g)
{/eq} | {eq}K_{eq} = \dfrac{\left [ CS_2 \right ]\left [ H_2 \right ]^4}{\left [ CH_4 \right ]\left [ H_2S \right ]^2}{/eq} | Expression | Biology & Chemistry | Senior High School | 73,545 |
698261 | An 18 mg strip of magnesium metal in 5.0 mL of 3.0 M HCl over a given time period. Evaluate the mol HCl/mol Mg ratio fro the reaction. | 2.02 | Float | Biology & Chemistry | Senior High School | 94,495 |
1494557 | You are studying a population of 365 mayflies growing exponentially and track the size of the population over a period of 3 generations. If 34 offspring are born in the first generation and 7 individuals die in the first generation, then what is the population size (rounded to the nearest whole number) at the end of your study? | 456 | Integer | Biology & Chemistry | Senior High School | 147,617 |
2044015 | How many times does a cell go through mitosis before it dies? | 50-70 | Integer | Biology & Chemistry | Senior High School | 207,654 |
1182729 | Balance the redox reaction occurring in acidic aqueous solution.
{eq}NO^-_3(aq) + Sn^{2+}(aq) \rightarrow Sn^{4+}(aq) + NO(g)
{/eq} | 3Sn^2+(aq) + 2NO3^- (aq) + 8H^+ (aq) → 3Sn^4+ (aq) + 2NO(g) + 4H2O(l) | Expression | Biology & Chemistry | Senior High School | 228,312 |
1148569 | Find the work done when 1 mole of calcium carbide reacts with water to produce acetylene. | 2477.6 J | Float | Biology & Chemistry | Senior High School | 199,268 |
402302 | Refer to the following reaction and table below:
{eq}2NO_2{(l)}+ Cl_{(l)} \rightarrow 2NO_2Cl_{(l)}
{/eq}
[NO2 ] (M)
[CI2 ] (M)
Initial Rate (M/s)
0.100
0.100
0.026
0.200
0.100
0.051
0.200
0.200
0.052
0.400
0.400
0.103
What is the value of the rate constant, k? | 0.26 | Float | Biology & Chemistry | Senior High School | 25,643 |
1166736 | Gold-198 has a half-life of 2.7 days. How much of a 681.0 mg gold-198 sample will remain after 13.5 days? | 21 g | Float | Biology & Chemistry | Senior High School | 120,627 |
775849 | Calculate the pH of a 2.0x10-3 M solution of H_2SO_4. | 2.398 | Float | Biology & Chemistry | Senior High School | 84,476 |
264521 | HClO is a weak acid (K{eq}_a{/eq} = 4.0 x 10{eq}^{-8}{/eq}) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.041 M in NaClO at 25 °C?
pH = _____ | 10.00 | Float | Biology & Chemistry | Senior High School | 52,141 |
518472 | A procaine salt solution is prepared by mixing 100ml of Procaine (0.5%(w/v) and 100mL of HCL (0.5mol.L). Using the structural formula of procaine, write the chemical reaction leading to salt formation. | See image in response. | Expression | Biology & Chemistry | University | 128,888 |
755585 | The value of the equilibrium constant Kp for the formation of ammonia, N2(g) + 3 H2(g) ↔ 2 NH3(g) is 4.5 x 10{eq}^{-5}
{/eq} at 450 degrees Celsius. What is the value of Kp for the following reaction?
2 NH3(g) ↔ N2(g) + 3 H2(g)? | 2.2e4 | Float | Biology & Chemistry | Senior High School | 18,088 |
1615970 | Given the reaction :
{eq}AB \rightarrow A + B
{/eq}
If the initial concentration of AB is 0.250 M, and the reaction mixture initially contains no products, what are the concentrations of A and B after 75s, {eq}k = 5.6 \times 10^{-2}
{/eq} | 0.09M | Float | Biology & Chemistry | Senior High School | 65,325 |
565900 | When aqueous solutions of {eq}NH_4OH(aq)
{/eq} and {eq}CuCl_2(aq)
{/eq} are mixed, the products are {eq}NH_4Cl(aq)
{/eq} and {eq}Cu(OH)_2(s)
{/eq}. What is the net ionic equation for this reaction? | 2OH^-(aq)+Cu^+(aq) -> Cu(OH)_2(s) | Expression | Biology & Chemistry | Senior High School | 213,772 |
693867 | An IRES and a riboswitch are somewhat different because one _____.
A. is part of mRNAs, the other is part of either tRNAs or rRNAs
B. binds the small subunit ribosome, the other binds ligands
C. has a secondary structure, the other has a tertiary structure
D. activates translation, the other inhibit translation | B | Multiple Choice | Biology & Chemistry | University | 217,529 |
2058161 | What is the density of Freon-11 (CFCl3) at 166 degrees Celsius and 5.92 atm? | 22.6 g/L | Float | Biology & Chemistry | Senior High School | 42,154 |
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