Which of the following does not have a fixed melting point/boiling point?

Which of the following are homogeneous in nature?

(i) ice (ii) wood

(iii) soil (iv) air

Two chemical substances X and Y combine together to form a product P which contains both X and Y

X + Y → P

X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following statements concerning X, Y and P are correct?

(i) P is a compound

(ii) X and Y are compound

(iii) X and Y are elements

(iv) P has a fixed composition

In the following set of substances, one item does not belong to the set. Select this item and explain why it does not belong to the set:

Hydrogen, Oxygen, Steam, Chlorine

Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.

(a) What type of substance is B?

(b) What type of substance is C?

(c) Name the gas (i) D, and (ii) E?

(d) Write one characteristic property of gas D.