The nucleus of an atom consists of _____.

1. 1. Only proton
   2. Protons and neutrons
   3. Protons + Electrons
   4. Proton + Neutron + Electron

A molecule is _____.

1. 1. The spectrum of a substance
   2. A small mass
   3. The smallest unit of a substance that retains the properties of the substance
   4. A class of organic compunds

A fuse wire is used to _____.

1. 1. Prevent an unduly high electric current to pass through a circuit
   2. Convert AC into DC
   3. Convert DC into AC
   4. To make the electrical circuit strong

In an earthen pot cooling of water depends upon _____.

1. 1. Wind
   2. Outside temperature
   3. Atmospheric humidity
   4. Galvanometer

Food is cooked quickly in a pressure cooker because _____.

1. 1. It absorbs heat quickly
   2. It retains heat for a long duration
   3. Boiling point of water id decreased
   4. Boiling point of water is increased

Fish plates are used in railway tracks _____.

1. 1. To connect two rails
   2. To control speed of the train
   3. To avoid tracks being distorted due to temperature fluctuation
   4. To keep the rails equidistant

A radar which detects the presence of an enemy aircraft uses _____.

1. 1. Radio-waves 
   2. Electric waves
   3. Sound waves
   4. Ultrasonic waves

In the process of galvanization an iron sheet is coated with _____.

1. 1. Tin
   2. Galena
   3. Tin
   4. Radio-waves 

What are ultrasonic waves?

1. 1. Sound waves produced in a vacuum
   2. Sound waves having frequency higher than audio-frequency range
   3. Sound waves having frequency shorter than audio-frequency range
   4. None of these

The process of transfer of heat by matter but without actual movement of the particles themselves is called _____.

1. 1. Radiation
   2. Convection
   3. Conduction
   4. All of these