Question

QUESTION 1

1. Which of the following solutions is a buffer?

   		A mixture  of HF and HBr
   		A mixture of H2SO4 and Na2SO4
   		A mixture of NaI and HI
   		A mixture of NaF and HF

1 points   

QUESTION 2

1. What is the [A^-]/[HA] ratio in a buffer made of HA and its conjugate base, A^-, and has a pH of 8.00 ? The pKa of HA is 6.00

   		1:1
   		1:10
   		1:100
   		10:1
   		100:1

1 points   

QUESTION 3

1. 3. If the molar solubility of the salt, Mg₃(PO₄)₂ is “s” mols/L, which of the following expression is correct at saturation point?

   		3[Mg2+] = s
   		[Mg3+] = 2s
   		[Mg2+] =3s
   		[PO43-] =3s

1 points   

QUESTION 4

1. A solution mixture contains equal concentrations of Cl^-, I^- and Br^- ions. If a dilute solution of Ag⁺ ions is slowly added to the mixture, what is the correct order with which the precipitates will form?(from first to last in precipitation) K_sp of : AgCl =1.8 ×10^-10, AgBr =5.0 ×10^-13 , AgI = 8.3 ×10^-17

   		AgCl,AgBr, AgI
   		AgI,AgCl,AgBr
   		AgCl,AgI, AgBr
   		AgI,AgBr,AgCl

1 points   

QUESTION 5

1. Methyl orange is an indicator with K_a= 1.0× 10^-4. Its acid form is red while its dissociated form is yellow. When it is used for a titration of aniline with HCl (HCl in buret) which has a pH at equivalence point 4.6 , what is the color change at endpoint.?

   		red to yellow
   		yellow to red
   		colorless to red
   		yellow to colorless

1 points   

QUESTION 6

1. The pH at equivalence point in a titration was found to be below 7.00 ( <7.00).Which of the following titration will it be?

   		Weak base vs strong acid
   		Strong base vs strong acid
   		Strong acid vs strong base
   		Weak acid vs strong base

1 points   

QUESTION 7

1. The reaction, A + B  → C + D has a rate law expression as rate = k[A]²B. If the concentration of B is doubled (assume concentration of A is unchanged) the rate of the

   reaction _______.

   		will decrease to half.
   		will be four times
   		will double
   		will be four times

1 points   

QUESTION 8

1. The reaction, 2A + B + 3C → 2X +   Y   is found to be zero order with respect to A, second order with respect to B and first order with respect to C. Which of the following is the correct rate law for the reaction?

   		k= rate[B]2[C]
   		rate= k[B]2[C]
   		rate= k[A][B]2[C]
   		rate = k[A]2[B][C]3

1 points   

QUESTION 9

1. A 25.00 mL sample of 0.2000 M hypochlorous acid (HOCl, K_a = 2.9 × 10^-8) is titrated with 0.2500 M KOH. What would be the pH at equivalence point?  

   		4.25
   		10.29
   		3.71
   		9.30

2 points   

QUESTION 10

1. 1. In the titration of a weak base vs strong acid , 40.00 mL acid was required to reach equivalence point. When exactly 20.00 mL of acid is added, the pH in the solution is found to be 7.28.What is the K_bof the weak base?

   		8.3 × 10-5
   		5.2× 10-8
   		3.2× 10-4
   		1.9× 10-7

2 points   

Answer 1