Question

State weather the following statement are true or false
c) Burning of fuel is an example of chemical change.
Ans:
d) Sodium carbonate is used to treat hard water.
Ans:
(e) Noble gases form only covalent bonds.
Ans:​

Answer 1

Answer:

c) true

d) false

e) false

Explanation:

c)Combustion is a chemical change since it involves a process in which a substance, in this case a fuel, reacts with oxygen in the air to give off heat. Therefore, burning fuel gives us a chemical change

d)Sodium carbonate, Na 2CO 3, is also known as washing soda. It can soften water that has temporary hardness and it can soften water that has permanent hardness. The calcium ions come from the hard water and the carbonate ions from the washing soda.

e)Because noble gases have full valency shell (8 electrons in outermost shell), which makes them chemically stable, and therefore have less tendency to lose or gain electrons. That's why they cannot form any bonds.