General Science Class 7

Which isotope is used to study the uptake of phosphorus containing fertilizers?

1. Phosphorus - 32
2. Carbon - 14
3. Lead - 210
4. Nitrogen - 15

Which isotope is used to determine the accumulation rates of pollutants in layers of soil?

1. Phosphorus - 32
2. Carbon - 14
3. Lead - 210
4. Nitrogen - 15

Carbon dating is used for the estimation of the age of:

1. Rocks
2. Fossils
3. Soil
4. Water

The symbolic representation of molecule of a compound is called?

1. Equation
2. Structure
3. Formula
4. Reaction

Chemical formula shows:

1. Number of atoms of each elements
2. Number of atoms in a compound
3. Number of atoms in a molecule
4. None

Which one of the following is not a sign of chemical change?

1. No change in composition
2. A release of gas
3. Change in colour, temperature, smell
4. Production of a new material

Which one of the following is not a sign of physical change?

1. Change that can be reversed
2. The substance does not turn into a new substance
3. A release of gas
4. None

A change in physical appearance or state of a substance is called:

1. Chemical Change
2. Physical Change
3. Nuclear Change
4. Biological Change

A change that alters the composition of a substances is known as ____?

1. Physical Change
2. Nuclear Change
3. Chemical Change
4. Biological Change

Which one among the following is not a chemical change?

1. Melting of ice
2. Burning of fuel
3. Explosion of firework
4. Cooking raw food