Question

a) Fill in the blanks:
1. The first period has elements and is……
said to be a period.
2. Atoms of same elements may differ from
one another are called……
3. The number of protons present in an atom is……
called at number of an atom.
14. An atom has the mass number 35 and the
atomic number 17 . The no. of neutrons in its
nucleus are ……
5. Hydro xides of group 1 elements are soluble in
water and form strong…… .
.b) Choose the correct answer!
1. An anhydrous salt which changes its colour
I when water is added to it is …… .
a) Nacı b) MgSO4 c) ZnCo d) Caso
2. According to the modern periodic law, the
properties of elements are the periodic function
of their ......... .
a) atomic size by mass number
c) atomic number d) size of nucleus.​

Answer 1

Explanation:

A)1) FIRST

2)ISOTOPES

3)ATOMIC NUMBER

14) 18 neutrons

5)Alkalies

B)1)(b)MgSo4

2)ATOMIC NUMBER(c)