When water is cooled to a temperature x, it gets converted into ice at temperature x by a process called P. And when ice at temperature x is warmed, it gets reconverted into water at the same temperature x in a process called Q.

(a) What is the value of temperature x in Kelvin?

(b) What is the process P known as?

(c) What is the name of energy released during process P?

(d) What is the process Q known as?

(e) What is the name of energy absorbed during process Q?

There are four substances W, X, Y and Z. The substance W is a dark violet solid having diatomic molecules. A solution of W in alcohol is used as a common antiseptic C. The substance X is a white solid which is usually recovered from sea water on a large scale. The substance Y is a white solid which is insoluble in water and used in the form of small balls for the safe storage of woollen clothes. The substance Z is a yet another white solid which is used in making commonly used dry cells.

(a) Name (i) W (ii) X (iii) Y and (iv) Z.

(b) Out of W, X, Y and Z, which substance/substances can undergo sublimation?

(c) Which substances organic in nature?

(d) What is the name of substance C?

(e) Which substance belongs to the halogen family?

The substance X normally exists in a physical state which can flow easily but does not fill its vessel completely. It also turns anhydrous copper sulphate blue. When substance X is cooled excessively, it changes into a substance Y which has a fixed shape as well as a fixed volume. If, however, the substance X is heated strongly, it changes into a substance Z which has neither a fixed shape nor a fixed volume.

(a) Name the substances (i) X (ii) Y and (iii) Z.

(b) What is the process of conversion of X into Y known as?

(c) At which temperature X gets converted into Y?

(d) What is the process of conversion of X into Z known as?

(e) At which temperature X gets converted into Z?

The scientists now say that there are actually five states of matter A, B, C, D and E. The state A has a fixed volume but no fixed shape. The state B can be compressed very easily by applying pressure and state C has a fixed shape as well as a fixed volume. The state D is mixture of free electrons and ions whereas state E is named after an Indian scientist and a famous physicist.

(a) Name the physical states (i) A (ii) B (iii) C (iv) D, and (v) E.

(b) Name one substance belonging to state C which can directly change into vapours on heating. What is this process known as?

(c) Name one substance which normally belongs to state B but whose solid form changes directly into gaseous state.

(d) Name the most common substance belonging to state A.

(e) Which state of matter makes the sum and other stars to glow.

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.

(a) How much is the value of x in Kelvin?

(b) What is the process R called?

(c) What is the name of the energy absorbed during the process R?

(d) What is process S known as?

(e) What is the name of energy released during the process S known as?