Question

What would you observe when a mixture of iron filings and sulphur powder is heated strongly?
A. Ferrous sulphide will be formed.
B. Iron filing would slightly change its color
C. Sulphur would slightly change the color
D. None of these

Answer 1

Chemical change occurs when a substance mixes with another and forms a new substance and physical change takes place without changing the composition of substances. The properties which can be measured or observed without changing the composition of the substance are known as physical properties.

Complete answer:
When iron filings and sulphur powder are mixed and heated, this would result in a chemical reaction leading to the formation of black ferrous sulphide.
Moreover, the ferrous sulphide formed has entirely different properties from $Fe$ and sulphur.
$Fe + S \to FeS$
The chemical reaction involved in the process when iron filings and sulphur powder are mixed and heated, is an example of combination reaction where two reactants i.e. iron filings and sulphur powder combine to form one product i.e. ferrous sulphide.
When iron filings and sulphur powder are mixed, their properties retain. Hence mixing of iron and sulphur is regarded as a physical change. But when iron filings and sulphur powder are mixed and heated they undergo chemical reactions leading to the formation of ferrous sulphide. So, heating of the mixture of iron filing and sulphur powder is regarded as a chemical change.
Ferrous sulphide will be formed when a mixture of iron filings and sulphur powder is heated strongly.

So, the correct answer is option A.

Note:
A compound is formed by combining two or more chemical elements but a mixture is created by two or more matter and it can be separated by the help of physical methods.
In a compound, a new product with entirely different properties are formed after the constituents or reactants are allowed to combine chemically and in mixture no new substance are formed.