chemistry mcqs test no 3


There are 10 Mcqs.Choose the best option.Write all of your answers in one comment (like 1A,2B,3B...)

1)The Haber process for the manufacture of ammonia is represented by the following equation.
N2(g) + 3H2(g) 2NH3(g)

∆H is –92 kJ mol–1

Which statement is correct about this reaction when the temperature is increased?
A Both forward and backward rates increase.
B The backward rate only increases.
C The forward rate only increases.
D There is no effect on the backward or forward rate.

2)Which mass of gas would occupy a volume of 3 dm3 at 25 °C and 1-atmosphere pressure? [1 mol of gas occupies 24 dm3 at 25 °C and 1atmosphere pressure.]
A 3.2 g O2 gas
B 5.6 g N2 gas
C 8.0 g SO2 gas
D 11.0 g CO2 gas

3)How does concentrated sulfuric acid behave when it reacts with sodium chloride?
A as an acid only
B as an acid and oxidising agent
C as an oxidising agent only
D as a reducing agent only

4)Which property of Group II elements (beryllium to barium) decreases with increasing atomic number?
A reactivity with water
B second ionisation energy
C solubility of hydroxides
D stability of the carbonates

5)Which element of the third period requires the least number of moles of oxygen for the complete combustion of 1 mol of the element?
A aluminium
B magnesium
C phosphorus
D sodium

6)Which reagent will give similar results with both butanone and butanal?
A acidified aqueous potassium dichromate(VI)
B an alkaline solution containing complexed Cu2+ ions (Fehling’s solution)
C an aqueous solution containing [Ag(NH3)2]+ (Tollens’ reagent)
D 2,4-dinitrophenylhydrazine reagent

7)Which compound exhibits both cis-trans and optical isomerism?
A CH3CH=CHCH2CH3
B CH3CHBrCH=CH2
C CH3CBr=CBrCH3
D CH3CH2CHBrCH=CHBr

8)Which equation represents the second ionisation energy of an element X?
A X(g) → X2+(g) + 2e–
B X+(g) → X2+(g) + e–
C X(g) + 2e– → X2–(g)
D X–(g) + e– → X2–(g)

9)Which factor helps to explain why the first ionisation energies of the Group I elements decrease from lithium to sodium to potassium to rubidium?
A The nuclear charge of the elements increases.
B The outer electron is in an ‘s’ subshell.
C The repulsion between spin-paired electrons increases.
D The shielding effect of the inner shells increases.

10)In the last century, the Haber process was sometimes run at pressures of 1000 atm and higher. Now it is commonly run at pressures below 100 atm.
What is the reason for this change?
A An iron catalyst is used.
B Maintaining the higher pressures is more expensive.
C The equilibrium yield of ammonia is increased at lower pressures.
D The rate of the reaction is increased at lower pressures.


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