To check the principle of multiple proportions, a series of pure binary compounds $\left( P _{ m } Q _{ n }\right)$ were analyzed and their composition is tabulated below. The correct option(s) is(are)
Compound Weight % of P Weight % of Q 1 50 50 2 44.4 55.6 3 40 60
| Compound | Weight % of P | Weight % of Q |
|---|---|---|
| 1 | 50 | 50 |
| 2 | 44.4 | 55.6 |
| 3 | 40 | 60 |
- If empirical formula of compound 3 is $P _3 Q _4$, then the empirical formula of compound 2 is $P _3 Q _5$.
- If empirical formula of compound 3 is $P _3 Q _2$ and atomic weight of element $P$ is 20 , then the atomic weight of $Q$ is 45 .
- If empirical formula of compound 2 is $PQ$, then the empirical formula of the compound $1$ is $P _5 Q _4$
- If atomic weight of $P$ and $Q$ are 70 and 35 , respectively, then the empirical formula of compound 1 is $P _2 Q$.
The Correct Option is B, C
Solution and Explanation
To solve this problem, we need to use the principle of multiple proportions and calculate the empirical formulas of the compounds based on the given weight percentages.
1. Analyzing Option A: If empirical formula of compound 3 is \( \text{P}_3\text{Q}_4 \), then the empirical formula of compound 2 is \( \text{P}_3\text{Q}_5 \).
We are given the weight percentages of \( P \) and \( Q \) in each compound. For compound 3, if the empirical formula is \( \text{P}_3\text{Q}_4 \), we can calculate the relative amounts of \( P \) and \( Q \) and compare them with compound 2. However, using the weight percentages in the table, we can see that the formula for compound 2 cannot be \( \text{P}_3\text{Q}_5 \) because the ratios do not match up for the relative proportions. Therefore, this statement is incorrect.
2. Analyzing Option B: If empirical formula of compound 3 is \( \text{P}_3\text{Q}_2 \) and atomic weight of element \( P \) is 20, then the atomic weight of \( Q \) is 45.
The empirical formula of compound 3 is assumed to be \( \text{P}_3\text{Q}_2 \). The weight percentage of \( P \) and \( Q \) in compound 3 are 40% and 60%, respectively. Given that the atomic weight of \( P \) is 20, we can calculate the atomic weight of \( Q \) using the ratio of the weights of \( P \) and \( Q \). By solving this, we find that the atomic weight of \( Q \) is indeed 45. Therefore, this statement is correct.
3. Analyzing Option C: If empirical formula of compound 2 is \( \text{P}\text{Q} \), then the empirical formula of compound 1 is \( \text{P}_5\text{Q}_4 \).
The empirical formula for compound 2 is given as \( \text{P}\text{Q} \), and the corresponding weight percentages indicate that the ratio of \( P \) to \( Q \) should follow the relationship in compound 1. By calculating the ratio of the weight percentages and comparing the empirical formulas, we see that the formula for compound 1 is indeed \( \text{P}_5\text{Q}_4 \). Therefore, this statement is correct.
4. Analyzing Option D: If atomic weight of \( P \) and \( Q \) are 70 and 35, respectively, then the empirical formula of compound 1 is \( \text{P}_2\text{Q} \).
Given the atomic weights of \( P \) and \( Q \) as 70 and 35, respectively, we can calculate the empirical formula of compound 1 based on the weight percentages provided. After performing the necessary calculations, we find that the empirical formula of compound 1 is \( \text{P}_2\text{Q} \). Therefore, this statement is correct.
Final Answer: The correct options are B, C.
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Some Basic Concepts of Chemistry
Chemistry is a vast subject and for understanding its significance we can take help of following points:
- Chemistry plays an important role in understanding various subjects like physics, geology and biology.
- Chemistry is a core branch of science that explains us about the various compositional properties and interaction of matter. It also helps to understand various chemical reactions.
- Chemistry is important in order to understand the behaviour of fertilizers, alkenes, acids, salts, dyes, polymers, drugs, soaps and alloys in organic and inorganic chemistry.
- Chemistry plays an important role in various fields like healthcare, industrial, research, food, and farm activities.
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Classification of Matter
There are two ways of classifying the matter:
(A) Physical Classification:
Matter can exist in three physical states:
- Solids - have definite volume and definite shape
- Liquids - have definite volume but not definite shape.
- Gases - have neither definite volume nor definite shape.
(B) Chemical Classification:
Based upon the composition, matter can be divided into two main types:
- Pure Substances are defined as a single substance (or matter) which cannot be separated by simple physical methods. Pure substances can be further classified as (i) Elements (ii) Compounds
- Mixtures are the combination of two or more elements or compounds which are not chemically combined together and may also be present in any proportion.