Atoms and Molecules — Science STD 9 — Question

Which of the following is not a postulate of Dalton's atomic theory

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

If 1.4g of calcium oxide is formed by the complete decomposition of calcium carbonate, then the amount of calcium carbonate taken and the amount of carbon dioxide formed will be respectively:

Separating funnel is used to separate immiscible liquids based on their:

The atomic number of an element E is 16. The number of electrons in ion E^2- will be:

1. 16
2. 18
3. 15
4. 14

An ionic compound will be formed by the combination of one of the following pairs of elements. This pair of elements is:

1. Chlorine and calcium.
2. Calcium and sodium.
3. Sulphur and carbon.
4. Chlorine and chlorine.

Which of the following is the seperation technique to seperate mercury and water:

You are given the following substances with their boiling and melting points.

Substance	Boiling Point (ºC)	Melting Point (ºC)
A	-183	-219
B	445	119
C	78	-15

Point out the physical states of A, B and C at room temperature (30°C).

The smell of food transfers across the room due to ____________?

If the number of electrons in an ion Z^3- is 10, the atomic number of element Z will be: