Tag: basic concepts of chemistry

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Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Among the following pairs of compounds, the one that illustrates the law of multiple proportions is:

  1. $NH _{3}$ and $NCl _{3}$
  2. $H _{2}S$ and $SO _{2}$
  3. $CuO$ and $Cu _{2}O$
  4. $CS _{2}$ and $FeSO _{4}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the concept of law of multiple proportions, if two elements chemically combine to give two or more compounds, then the weight of one element which combines with the fixed weight of the other element in those compound, bear simple multiple ratios to one another.


Hence, $CuO$ and $CU _2O$ form two different compounds in a ratio of 1:2 with the fixed weight of oxygen.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

The % composition of four hydrocarbons are as follows:


(i) (ii) (iii) (iv)
%C 75 80 85.7 91.3
%H 25 20 14.3 8.7


The data illustrates the law of:

  1. constant proportion

  2. conservation of mass

  3. multiple proportion

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

The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers. This table shows different hydrocarbons, illustrating this law.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

The % of hydrogen in water and hydrogen peroxide is $11.2$ % and $5.94$ % respectively. This illustrates the law of:

  1. constant proportions

  2. conservation of mass

  3. multiple proportions

  4. law of gaseous volume.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The law of multiple proportions say that if two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. 

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

The oxides of nitrogen contain 63.65%, 46.69% and 30.46% of nitrogen by weight, respectively. This data illustrates the law of:

  1. constant proportions

  2. multiple proportions

  3. reciprocal proportions

  4. conservation of mass
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The law of multiple proportions say that If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.
Here, the ratios of oxygen which react with a constant mass of N are $2:3 , 2:1$ and $4:3$ respectively.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

The ratio between the different weights of oxygen in different compounds which combine with the same weight of nitrogen ($14$ parts) is $8:16:24:32:40$ or $1:2:3:4:5$.
This is simple whole number which supports the law of:

  1. conservation of mass

  2. multiple proportion

  3. constant composition

  4. reciprocal proportion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The answer is multiple proportion.
When two elements combine to from two or more than two compounds, the weights of one of the element which combine with a fixed weight of the other, bear a simple whole number ratio is the law of multiple proportion and the given example supports the law.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Different proportions of oxygen in the various oxides of nitrogen proves the law of:

  1. equivalent proportions

  2. conservation of mass

  3. multiple proportions

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

The existence of multiple oxides of nitrogen (like NO, NO2, N2O) where different masses of oxygen combine with a fixed mass of nitrogen is the definition of the law of multiple proportions.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

0.75 mole of solid ‘$A _4$’ and 2 moles of gaseous $O _2$ are heated in a sealed vessel, completely using up the reactants and producing only one compound. It is found that when the temperature is reduced to the initial temperature, the contents of the vessel exhibit a pressure equal to half the original pressure. What conclusions can be drawn from these data the product of the reaction?

  1. $A _2O _5$
  2. $A _3O _4$
  3. $A _2O _2$

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
give reaction
$A _4(s) + O _2(g) → A _xO _y$

Applying POAC  law for A atoms,
4 × moles of $A _4  =  x \times moles of A _xO _y$
=> $4 \times 0.75 = x \times  1$
=> x = 3

Applying POAC for O atoms,
$2\times  moles of O _2 = y \times moles of A _xO _y$
=> $2 \times 2 = y \times 1$
=> y = 4

Thus, the formula of the product is $A _3O _4$.