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Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

When hydrogen and oxygen combine to form water, they form:

  1. an unstable compound

  2. a stable mixture

  3. an unstable mixture

  4. an extremely stable compound
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When hydrogen and oxygen combine to form water, they form water an extremely stable compound. We can say water is a stable compound because tremendous energy is released is a signal that hydrogen and oxygen are very eager to become water or in another way it is very hard to break water molecules apart into its components.

$2H _2+O _2\longrightarrow 2H _2O$

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

In ammonia, nitrogen and hydrogen always combine in $14:3$ ratio by mass. This is in agreement with :

  1. Law of conservation of mass

  2. Law of definite proportion

  3. Law of multiple proportion

  4. Law of combining volume
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Law of definite proportion states that elements always combine in the definite ratio by mass. So it is in agreement with the law of definite proportion.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

Law of definite proportion does not apply to nitrogen oxide because:

  1. Atomic weight of nitrogen is not conserved

  2. Molecular weight of nitrogen is variable

  3. Equivalent weight of nitrogen is variable

  4. Atomic weight of oxygen is variable
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nitrogen forms multiple compounds with oxygen. Hence, we cannot apply the law of definite proportion to nitrogen oxide.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

A solution of copper oxide was prepared by heating, igniting and precipitation. Which of the following method will give higher ratio of copper oxide?

  1. Heating

  2. Precipitation

  3. Ignition

  4. All of the above will give the same ratio
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a compound the ratio of the atoms or element by mass remains always same irrespective of the source of compound. This means a certain compound always formed by the combination of atoms in same ratio by mass. Hence, copper oxide made from any method will always give the same ratio of copper oxide.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

In a compound the ratio of the atoms or element by mass remains always same irrespective of :

  1. temperature

  2. nature of compound

  3. source of compound

  4. size of compound
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Compounds are formed by the combination of two or more elements. In a compound the ratio of the atoms or element by mass remains always same irrespective of the source of compound. This means a certain compound always formed by the combination of atoms in same ratio by mass. If the ratio of mass of constituent atoms will be altered the new compound is formed.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

If the ratio of the atoms by mass is altered then :

  1. new compound formed

  2. same compound are formed

  3. no reaction takes place

  4. state of compound are changed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a compound the ratio of the atoms or element by mass remains always same irrespective of the source of compound. This means a certain compound always formed by the combination of atoms in same ratio by mass. If the ratio of mass of constituent atoms will be altered the new compound is formed.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

Law of constant proportion states that :

  1. a chemical compound always contains exactly the same proportion of elements by mass.

  2. mass can neither be created nor destroyed in a chemical reaction.

  3. when two elements combine with each other to form two or more than two compounds, the masses of one the element which combines with the fixed mass of the other, bears a simple whole number ratio.

  4. total mass of products is always equal to the total mass of reactants.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Law of Constant Proportion states that a chemical compound always contains exactly the same proportion of elements by mass. This law is also known as Law of definite proportions. Joseph Louis Proust gave this law hence, this law is also known as Prousts Law.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions
Four different experiments were conducted in the following ways-

I) $3g$ of carbon was burnt in $8g$ of oxygen to give $11g$ of $CO _2$

II) $1.2g$ of carbon was burnt in air to give $4.2g$ of $CO _2$,

III) $4.5g$ of carbon was burnt in enough air to give $11g$ of $CO _2$

IV) $4g$ of carbon was burnt in oxygen to form $30.3g$ of $CO _2$


Law of constant proportions is illustrated in which of the following experiment(s)?

  1. I and III only

  2. II and III only

  3. IV only

  4. I only
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The law of constant proportions states that a chemical compound always contains its component elements in a fixed ratio by mass. Experiment I shows 3g C + 8g O2 = 11g CO2, a ratio of 3:8. Experiment III also shows 4.5g C + 6.5g O2 = 11g CO2, which is not 3:8, but the question asks for the experiment illustrating the law. Experiment I is the standard demonstration.