Question

Which of the following are true for an element? (i) Atomic number = number of protons + number of electrons (ii) Mass number = number of protons + number of neutrons (iii) Atomic mass = number of protons = number of neutrons (iv) Atomic number = number of protons = number of electrons

Which of the following statement is always correct?

What information do you get from the Fig. 4.4 about the atomic number, mass number and valency of atoms X, Y and Z? Give your answer in a tabular form.

Complete the Table 4.1 on the basis of information available in the symbols given below (a) ³⁵₁₇Cl (b) ¹²₆C (c) ⁸¹₃₅Br