Question

6) Which of the following are indicators that a chemical change has occurred in a substance?
(a) Irreversibility of a substance after heating
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(b) A substance breaking into smaller pieces of itself
(c)The expansion in size of a material upon being heated
(d) A substance not resuming its original shape, after being pressed​

Answer 1

Amongst the following (a) is an indicator that a chemical change has occurred in a substance.

• Chemical change is usually irreversible chemical reaction involving atom rearrangement and a change in chemical characteristics or composition of one or more compounds, culminating in the production of at least one new substance.
• A substance breaking into smaller pieces of itself is a physical change.
• The expansion in size of a material upon being heated is physical change.
• A substance not resuming its original shape, after being pressed is a physical change.

Answer 2

(a) Irreversibility of a substance after heating are indicators that a chemical change has occurred in a substance

Explanation:

Irreversibility of a substance after heating:

• Changes that are irreversible are irreversible. They are irreversible. You can't, for example, return a cake to its original ingredients.

A substance breaking into smaller pieces of itself:

• If you spend any time in a chemistry lab, you will almost certainly come across a Bunsen burner, which is a gas burner that is useful when trying to make chemical changes.  Heat is a form of energy that can cause substances to decompose.
• As a result, the compounds can be divided into smaller pieces.

The expansion in size of a material upon being heated:

• Each material's thermally induced change in the length of a thin strip of metal is different. When heated, a strip of steel, for example, expands half as much as an equal length of aluminium.
• Welding a tiny piece of each of these materials together creates.

A substance not resuming its original shape, after being pressed​:

• A physical change, such as changing states or dissolving, does not result in the formation of a new material; but, a chemical change does. The atoms and molecules that interact in a chemical reaction are referred to as reactants.
• There are no new atoms formed, and there are no atoms destroyed.