Tag: basic concepts of chemistry

Questions Related to basic concepts of chemistry

One part of an element (A) combines with two parts of another element (B). Six parts of element (C) combines with 4 parts of (B). If (A) and (C) combine together, then the ratio of their weights will be governed by:

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. law of definite proportion

  2. law of multiple proportion

  3. law of reciprocal proportion

  4. law of conservation of mass

Show answer
Correct Option: C
Explanation:

Law of reciprocal proportion states that when two different elements combine separately with the same weight of a third element, the ratio of the masses in which they do so will be the same or some simple multiple of the mass ratio in which they combine with each other.

Different proportions of oxygen in the various oxides of nitrogen, prove the law of:

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. reciprocal proportions

  2. multiple proportions

  3. constant proportions

  4. conservation of mass

Show answer
Correct Option: B
Explanation:

Different proportion of oxygen in the various oxides of nitrogen proves the law of multiple proportions, which states:

when two elements combine in more than one proportion to form one or more compounds, the weight of one element that combine with the given weight of other elements are in the ratio of small whole number.


Which one of the following sets of compound correctly illustrates the law of reciprocal proportions?

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. $P _2O _3, PH _3, H _2O$

  2. $P _2O _5, PH _3, H _2O$

  3. $N _2O _5, NH _3, H _2O$

  4. $N _2O, NH _3, H _2O$

  5. $NO _2, NH _3, H _2O$

Show answer
Correct Option: B
Explanation:

In $PH _3$, the ratio by weight of $P:H=31:3$

For $H _2O, O:H= 16:2=8:1$
Keeping the weight of $H(=1)$ fixed, $P:O=\cfrac {31}{3}:\cfrac {8}{1}=31:24\longrightarrow (1)$
In $P _2O _5, P:O$ is $(2 \times 31):(5 \times 16)$
$=62:80$ or $31:40 \longrightarrow (2)$
Keeping the weight of $P(=31)$ fixed in equation (1) & (2), the ratio of oxygen is $24:40$ or $3:5$ which is a simple ratio.

One of the following combinations illustrates the law of reciprocal proportion-

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. ${N _2}{O _3},{N _2}{O _4}{N _2}{O _5}$

  2. $PaCI,NaBr,NaI$

  3. $N{S _2},C{O _2},S{O _2}$

  4. $P{H _3},{P _2}{O _3},{P _2}{O _5}$

Show answer
Correct Option: A

$H _2S$ contains $94.11\%$ sulphur; $SO _2$ contains $50\%$ oxygen and $H _2O$ contains $11.11\%$ hydrogen. Thus :

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. law of multiple proportions is followed.

  2. law of reciprocal proportions is followed.

  3. law of conservation of mass is followed.

  4. all of the above are followed

Show answer
Correct Option: B
Explanation:

The Law of Multiple Proportions : It was given by Dalton. When one element combines with the other element to form two or more different compounds, the mass of one elements, which combines with a constant mass of the other, bear a simple ratio to one another.
$N _2O, NO, NO _2$
The law of reciprocal proportions states that, when two different elements separately combine with a fixed mass of a third element, the proportions in which they combine with one another shall be either in the same ratio or some multiple of it. For example, sulphur and carbon both form compounds with hydrogen. In methane 12g of carbon react with 4g of hydrogen. In hydrogen sulphide, 32g of sulphur react with 2g of hydrogen (i.e. 64g of S for 4g of hydrogen). Sulphur and carbon form a compound in which the C: S ratio is 12:64 (i.e. $CS _2$).

Which of the following statements are correct?

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. French chemist A. Lavoisier is called the father of chemistry and proposed the law of conservation of mass.

  2. French chemist Joseph Proust proposed the law of definite proportions.

  3. Dalton proposed the law of multiple proportions.

  4. Richter proposed the law of reciprocal proportions.

Show answer
Correct Option: A,B,C,D
Explanation:

A) French chemist A. Lavoisier is called the father of chemistry and proposed the law of conservation of mass. (True)

B) French chemist Joseph Proust proposed the law of definite proportions. (True). The Law of Definite proportions, states that a chemical compound always contains exactly the same proportion of elements by mass.

C) Dalton proposed the law of multiple proportions. (True). John Dalton (1803) stated, "'When two elements combine with each other to form two or more compounds, the ratios of the masses of one element that combines with the fixed mass of the other are simple whole numbers.

D) Richter proposed the law of reciprocal proportions. (True). (The law of reciprocal proportions was proposed by Jeremias Richter in 1792. It states that "If two different elements combine separately with the same weight of a third element, the ratio of the masses in which they do so are either the same or a simple multiple of the mass ratio in which they combine".

12 g of $\displaystyle X _{2}O _{5}$ an oxide of element X contains 7.2 g of X. How many moles of X does 7.2 g of the element contain ?

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. 6

  2. 0.5

  3. 0.12

  4. 4.5

Show answer
Correct Option: C

The weight ratio of two elements A and B which combine with the fixed weight of C separately is either the same or some simple whole number multiple of the weight ratio in which A and B combine together. This statement explains :

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. law of multiple proportion.

  2. law of reciprocal proportion.

  3. law of conservation of mass.

  4. law of constant composition.

Show answer
Correct Option: B
Explanation:

The weight ratio of two elements A and B which combine with the fixed weight of C separately is either the same or some simple whole number multiple of the weight ratio in which A and B combine together. This statement explains the Law of reciprocal proportion.
For example, 23 g of $Na$ combines with 35.5 g of $Cl$ and 1 g of $H$ to form $NaCl$ and $NaH$. Hence, 35.5 g of $Cl$ and 1 g of $H$ will combine to form $HCl$.

Lead form 2 oxides. the two oxides were subjected to reduction with carbon separately:


Oxide 1: Original mass: 8.92 gm
               Loss in mass: 0.64 gm

Oxide 1: Original mass: 119.5 gm
               Loss in mass: 16 gm

The data illustrates:

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. Law of multiple proportion

  2. Law of constant composition

  3. Law of variable proportion

  4. Law of reciprocal proportion

Show answer
Correct Option: B
Explanation:

In experiment $A-$ Oxide of $Pb=8.92g$


Mass of $Pb$ after reduction $=8.92g-0.64g=8.28g$


Ratio of oxide of $Pb$ to $Pb=\cfrac{8.92}{8.28}=\cfrac{1.077}{1}$

In experiment $B-$ Oxide of $Pb=119.5g$

After reduction, $Pb=119.5-16=103.5g$

Ratio of oxide of $Pb$ to $Pb=\cfrac{119.5}{103.5}=\cfrac{1.15}{1}$

The data illustrates the law of constant proportion.


Hence, the correct option is $\text{B}$

Law of reciprocal proportion was proposed by:

law of reciprocal proportion laws of chemical combination basic concepts of chemistry some basic concepts of chemistry chemistry

  1. Antoine Lavoisier

  2. Jeremias Ritcher

  3. James Rutherford

  4. John Dalton

Show answer
Correct Option: B
Explanation:

Law of reciprocal proportion was proposed by J. Richter according to which If two different elements combine separately with the same weight of a third element, the ratio of the masses in which they do so are either the same or a simple multiple of the mass ratio in which they combine.