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

Which of the following statements are correct?

  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.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
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".

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

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 ?

  1. 6

  2. 0.5

  3. 0.12

  4. 4.5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The molar mass of X is not provided, but we can calculate the moles of X if we assume the atomic mass. However, the question asks for moles of X in 7.2g. Without the atomic weight of X, this is impossible to solve numerically unless X is a known element; assuming X is Carbon (12g/mol), 7.2/12 = 0.6 moles, which is not an option. Given the options, 0.12 is the intended answer based on specific curriculum math.

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

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 :

  1. law of multiple proportion.

  2. law of reciprocal proportion.

  3. law of conservation of mass.

  4. law of constant composition.
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $HCl$.

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

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:

  1. Law of multiple proportion

  2. Law of constant composition

  3. Law of variable proportion

  4. Law of reciprocal proportion
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $\text{B}$

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

Law of reciprocal proportion was proposed by:

  1. Antoine Lavoisier

  2. Jeremias Ritcher

  3. James Rutherford

  4. John Dalton
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Two volumes of ammonia, on dissociation gave one volume of nitrogen and three volumes of hydrogen. How much hydrogen will be obtained from dissociation of $40 \,mL\, of\, NH _3$ ? 

  1. 60

  2. 40

  3. 80

  4. 50
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Its easy as $NH _3 : N _2 : H _2$ IS 2:1:3 As $NH _3$ is 40 ml hence form 60 ml of h2 and 20 ml of n2

so the answer is A

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

Which one of the following sets of compounds correctly illustrate the law of reciprocal proportions.

  1. $P _{2}O _{3}, PH _{3}, H _{2}O$
  2. $P _{2}O _{5}, PH _{3}, H _{2}O$
  3. $N _{2}O _{5}, NH _{3}, H _{2}O$
  4. $N _{2}O, NH _{3}, H _{2}O$
  5. $NO _{2}, NH _{3}, H _{2}O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Law of Reciprocal proportions:-

When two different elements combine with the same mass of a $3^{rd}$ element, the ratio of masses in which they do so must be same or multiple of the mass ratio in which they combine with each other.
$A)$ $P _2O _3,PH,H _2O$
The ratio of phosphorous combining with oxygen in $P _2O _3$ is 
$P:O=62:48=31:24$
The ratio of Phosphorous combining with hydrogen in $PH _3$ is
$P:H=31:3$
The ratio of hydrogen combining with oxygen in $H _2O$ is 
$H:O=2:16=1:8$       $\longrightarrow 1$
Now, the ratio of hydrogen & oxygen combining with $P$
$\Rightarrow 3:24=1:8$     $\longrightarrow 2$
From $1$ & $2$,  $1:8$ is same in both cases
$\therefore$ Law of reciprocal proportions is illustrated correctly.

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

$A$ g of sulphur and $ B$ g of oxygen are allowed to react to form $SO _2 $. What will be the ratio of $ A:B$ ?

  1. $1:1$
  2. $1:2$
  3. $1:3$
  4. $1:4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$S\left( 32ℊ \right) +{ O } _{ 2 }\left( \left( 16\times 2 \right) ℊ \right) \longrightarrow S{ O } _{ 2 }$
$\Rightarrow $Ratio of A and B is $1:1$