Matter in Our Surroundings — Science STD 9 — Question

When water is heated to a temperature x, it gets converted into steam at temperature x by a process called R. And when steam at temperature x is cooled, it gets reconverted in to water at the same temperature x by a process called S.

1. How much is the value of x in Kelvin?
2. What is the process R called?
3. What is the name of the energy absorbed during the process R?
4. What is process S known as?
5. What is the name of energy released during the process S known as?

The valencies (or charges) of some of the ions are given below:

Ion	Valency(Charges)	Ion	Valency(Charge)
Sodium ion	1+	Bromide ion	1-
Ammonium ion	1+	Hydroxide ion	1-
Calcium ion	2+	Sulphate ion	2-
Lead ion	2+	Phosphate ion	3-

Using this information, write down the formulate of the following compounds:

1. Sodium phosphate.
2. Ammonium sulphate.
3. Calcium hydroxide.
4. Lead bromide.

State two observations which show that atom is not indivisible.

Explain why, steam at 100°C is better for heating purposes than boiling water at 100°C.

Write the electronic configuration of any one pair of isotopes and isobars.

Define mole. What are the two things that a mole represents?

Name the three states of matter. Give one example of each.

Out of four gases Cl₂, CO₂, CH₄, N₂, which gas would diffuse most rapidly and why?

Compare the properties of metals and non-metals with respect to:

1. Malleability.
2. Ductility.
3. Electrical conductivity.