Practice Pakistan's most useful MCQs for competitive exams

A compound was found having nitrogen and oxygen in the ratio 28 gm and 80 gm respectively. The formula of the compound is_________________?

• (A)  N2O4
• (B)  N2O5
• (C)  N2O3
• (D)  None of these

Answer

Submitted By :Ali Uppal

With rise in temperature, the heat capacity of a substance___________________?

• (A)  Increases
• (B)  Decreases
• (C)  Remains unchanged
• (D)  Either

Answer

Submitted By :Ali Uppal

One of the specific gravity scales is “Brix” (used specifically for sugar solution). It is defined as ______________?

• (A)  Brix = (400/G) – 400
• (B)  Brix = 200 (G-1)
• (C)  Brix = 145 – (145/G)
• (D)  None of these

Answer

Submitted By :Ali Uppal

A gas at 0°C is cooled at constant pressure until its volume becomes half the original volume. The temperature of the gas at this state will be_______________?

• (A)  -136.5°C
• (B)  – 136.5°K
• (C)  -273°C
• (D)  0°K

Answer

Submitted By :Ali Uppal

The heat evolved in the combustion of benzene is represented by the equation: C6H6 + 7.5 O2 = 6CO2 + 3H2O, ΔH = 3264.6 kJ/kg. mole The heat energy change, when 39 gm of C6H6 is burnt in an open container, will be _____________ kJ/kgmole?

• (A)  +816.15
• (B)  +1632.3
• (C)  -1632.3
• (D)  -2448.45

Answer

Submitted By :Ali Uppal

A solution having a pH value of 5 is less acidic than the one having a pH value of 2 by a factor of ________________?

• (A)  3
• (B)  100
• (C)  1000
• (D)  None of these

Answer

Submitted By :Ali Uppal

Heat of ____________ of a fuel is called its calorific value?

• (A)  Formation
• (B)  Combustion
• (C)  Reaction
• (D)  Vaporisation

Answer

Submitted By :Ali Uppal

The gravimetric (i.e., by weight) composition of a vapor saturated gas is independent of the_______________?

• (A)  Nature of both the gas & the liquid
• (B)  Temperature
• (C)  Total pressure
• (D)  None of these

Answer

Submitted By :Ali Uppal

The heats of vaporisation of CS2, C2H5OH &H2O are 26.8, 38.6 & 40.6 KJ/kg.mole respectively. The order of decreasing inter-molecular forces in these liquids is________________?

• (A)  H2O > C2H5OH > CS2
• (B)  CS2 > C2H5OH > H2O
• (C)  H2O > CS2 > C2H5OH
• (D)  CS2 > H2O > C2H5OH

Answer

Submitted By :Ali Uppal

Pick out the wrong unit conversion of thermal conductivity ?

• (A)  1 BTU/ft2.hr.°F/ft = 1.488 kcal/m2. hr.°C/m
• (B)  1 BTU/ft2.hr.°F/inch = 1.488 kcal/m2. hr.°C/m
• (C)  1 kcal/m.hr.°C = 0.672 BTU/ft.hr.°F = 1.163 W/m. °K
• (D)  1 W/cm.°C = 85.985 kcal/m.hr.°C = 57.779 BTU/ft.hr.°F

Answer

Submitted By :Ali Uppal