The echo (reflected sounD. will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least ________?

A. 1120 ft
B. 120 ft
C. 56 ft
D. 100 ft
E. None of these

In winter an iron pipe feel colder than a wooden window . This is because wood is_______?

A. Conductor
B. Non-Conductor
C. Semi- Conductor
D. Not a solid while iron is a solid
E. None of these

Water is heated in a kettlE. The inside water is heated by convection. A person sitting near the fire receives heat by ________?

A. Conduction
B. Convection
C. Radiation
D. Reflection
E. None of these

Name the famous book of Ibn-Sina in which he discussed human physiology and medicine ?

A. Al-Qanun
B. Al-Masudi
C. New Renaissance
D. Tadhkira
E. None of these

In a railway track, two rails are joined end to end with a gap tin between them because?

A. Steel can be saved
B. Accidents due to contraction in winter can be avoided
C. Air gaps are necessary for bearing the weight of running train
D. Accidents due to expansion in summer can be avoided
E. All of these

A. Parasite
B. Scavenger
C. Predator
D. Mammal
E. None of these

A. Seedless fruits
B. Parthenogenesis fruits
C. Parthenocarpic fruits
D. placental fruits
E. Organic fruits

Quartz crystal in quartz watches work on the principle called?

A. Photoelectric effect
B. Stark effect
C. Thermionic effect
D. Piezo-electric effect
E. None of these

A. Glaciers
B. Desert
C. Islands
D. Volcanoes
E. Fertile land

A. Carbon dioxide
B. Sugar
C. Bacteria
D. Oxygen
E. None of these