Chemistry
Assertion (A): PCl3, is known as phosphorus trichloride while AlCl3, is aluminium chloride and not aluminium trichloride.
Reason (R) : Phosphorus shows variable valency. Aluminium does not show variable valency
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Phosphorus can show variable valency (like 3 and 5), so we name its compounds with prefixes like phosphorus trichloride (PCl3).
Aluminium, however, shows a fixed valency of 3, so AlCl3 is simply called aluminium chloride without needing a prefix. Hence, both assertion (A) and reason (R) are true, and reason (R) correctly explains assertion (A).
Related Questions
Assertion (A): An atom is the smallest part of matter which can take part in a chemical reaction.
Reason (R): Atoms of every element can exist independently.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): All equations need to be balanced.
Reason (R): An unbalanced equation would imply that atoms have been created or destroyed.
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- A is false but R is true.
Assertion (A): In a chemical reaction, the total mass of the products remains the same as that of the reactants.
Reason (R): A chemical reaction involves a simple exchange of partners and no new species are formed.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Magnesium phosphate is written as Mg3(PO4)2.
Reason (R): The valencies of magnesium and phosphate are three and two respectively.
- Both A and R are true and R is the correct explanation of A.
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- A is true but R is false.
- A is false but R is true.