Practice Pakistan's most useful MCQs for competitive exams

Which of the following is resistant to the action of both heat & chemicals ?

• (A)  Borosilicate glass
• (B)  Silica glass
• (C)  Soda lime glass
• (D)  None of these

Answer

Submitted By :Ali Uppal

Two solutions A1 & A2 have pH value of 2 & 6 respectively. It implies that the solution ?

• (A)  A1 is more alkaline than solution A2
• (B)  A1 is highly acidic
• (C)  A2 is very slightly acidic
• (D)  Both

Answer

Submitted By :Ali Uppal

________________ is the hardest material out of the following ?

• (A)  Boron carbide
• (B)  Tungsten carbide
• (C)  Hardened steel
• (D)  Silicon carbide

Answer

Submitted By :Ali Uppal

_______________ is the most important element, which controls the physical properties of steel ?

• (A)  Manganese
• (B)  Silicon
• (C)  Carbon
• (D)  Vanadium

Answer

Submitted By :Ali Uppal

The taper provided on pattern for its easy & clean withdrawal from the mould is termed as the _______________ allowance ?

• (A)  Casting
• (B)  Pattern
• (C)  Draft
• (D)  Distortion

Answer

Submitted By :Ali Uppal

A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is ________________ W/m2 °C ?

• (A)  50
• (B)  100
• (C)  150
• (D)  200

Answer

Submitted By :Ali Uppal

In the X-ray radiography technique, the tube voltage for thicker plates as compared to thin plates, should be________________?

• (A)  Higher, as it gives higher wavelength
• (B)  Lower, as it gives higher wavelength
• (C)  Higher, as it gives shorter wavelength
• (D)  Lower, as it gives shorter wavelength

Answer

Submitted By :Ali Uppal

What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively ?

• (A)  2
• (B)  8
• (C)  10
• (D)  40

Answer

Submitted By :Ali Uppal

The critical pressure at which the latent heat of vaporization of steam becomes zero is _____________ Kg/cm2 ?

• (A)  273.15
• (B)  225.65
• (C)  100.03
• (D)  373.15

Answer

Submitted By :Ali Uppal

The diffusion co-efficient of Ni in Cu at 1000 K is 1.93 × 10-16 m2S-1 and it is 1.94 × 10-14 m2S- 1 at 1200 K. The activation energy (in k. J.mole-1) for the diffusion of Ni in Cu is_________________?

• (A)  130
• (B)  180
• (C)  230
• (D)  250

Answer

Submitted By :Ali Uppal