Question

II. Fill in the blanks with appropriate words:
1. A pure substance always have______ composition
2. Elements which emit harmful radiations are ______ known as
elements.
3 ______ are electropositive elements.​

Answer 1

Answer:

1 definite and constant

2 radioactive elements

3 Metals like Na, Mg, K, Ca, Fe, Zn lose electrons and form positively charged ion.