My suggested answer:
Q21) D
Q22) C
Q23) D
Q24) C
Q25) A
Q26) B
Out of the 20 chemistry question, the question I like most will be this. On the surface it looked simple, but it's testing Limiting reactant, and calculation of excess reactant.
First step is to determine the molecular formula. After you've done with your calculation, you'll get FeS.
Then next is to find out which is the the limiting reactant. After the calculation, you'll know that Fe is the limiting reactant, and of course S is in excess.
No. of mol of FeS/ No. of mol of Fe = 1/1 = 1
No. of mol of FeS = 1 x 0.125 = 0.125 mol
Mass of FeS = 0.125 x (56 + 32) = 11g
Final step is to fine out the mass of excess reactant(S).
As calculated earlier(not shown here), take the no. of mole of S minus the no. of moles of Fe. Which is 0.219 - 0.125 = 0.094 moles of S in excess
Then 0.094 x 32(Ar of S) = 3.
Answer: B
Q27) D
Q28 ) B
Q29) D
Q30) C
Q31) A
Q32) D
Q33) A
Q34) C
Q35) C
Q36) C
Q37) A
Q38 ) B
Q39) A
Q40) B
Edited for Q34, thanks kester for pointing out my mistake.
