The substances are radioactive which have _____.

1. 1. Electrons in their nuclei
   2. Nuclei with less number of neutrons
   3. Unstable nuclei
   4. Electrons removed from the outermost shell

On addition of salt to water, its _____.

1. 1. freezing point increases
   2. boiling point is not affected
   3. boiling point decreases
   4. boiling point increases

Which of the following gases does not pollute air?

1. 1. Nitrogen dioxide
   2. Carbon dioxide
   3. Carbon monoxide
   4. Sulphur dioxide

Which one of the following has the highest fuel value?

1. 1. Charcoal
   2. Hydrogen
   3. Gasoline
   4. Natural gas

The inorganic natural resource of the earth is _____.

1. 1. wood
   2. mineral fuels
   3. coal
   4. microbes

On descending a group in a periodic table electropositive character of elements _____.

1. 1. decreases
   2. remains same
   3. increases
   4. None of these

Most of the known elements are _____.

1. 1. Non-metals
   2. Metals
   3. Transition metals
   4. Inner transition metals

With the rise in temperature, conductivity of metals _____.

1. 1. increases
   2. decreases
   3. remains unchanged
   4. may decrease or increase

During electrolysis, metals are deposited at the cathode, because the cathode _____.

1. 1. undergoes oxidation
   2. withdraw electrons
   3. supplies electrons
   4. None of the above

Milk can be preserved by a few drops of _____.

1. 1. Formic acid solution
   2. Acetic acid solution
   3. Formaldehyde solution
   4. Acetaldehyde solution