Atoms and Molecules — Science STD 9 — Question

The atomic number of calcium and argon are 20 and 18 respectively, but the mass number of both these elements is 40. What is the name given to such a pair of elements?

The atomic theory of matter was proposed by:

1. John Kennedy.
2. Lavoisier.
3. Proust.
4. John Dalton.

Isotopes of an element have:

Identify the sub-atomic particle(s) with no charge and relative mass equal to one among the following:

The dyes present in fountain pen ink can be separated by the technique of:

1. Fractional distillation.
2. Infrared photography.
3. Crystallization.
4. Chromatography.

For each of the following, use letters to indicate wheather the matter is element (E), compound (C) or mixture (M).

S.No.	Matter	Classification
1.	Water
2.	Mercury
3.	Air
4.	Tin

One of the following represents the solution of solid in a solid. This one is:

1. Boron.
2. Brass.
3. Beryllium.
4. Bread.

The triad which is isoelectronic:

The symbol for SI unit of mole is:

Which is the most effective method of separating mixtures of miscible volatile liquids?