Tag: general introduction: importance and scope of chemistry

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Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Who defined element as basic form of matter that cannot be broken down into simpler substances by chemical reactions?

  1. Wilhelm Weins

  2. William J. Crooke

  3. Antonie L. Lavoisier

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

Antonie L. Lavoisier defined element as basic form of matter that cannot be broken down into simpler substances by chemical reactions

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Which one of the following is a compound?

  1. The black residue left when sugar is charred

  2. Nitrogen gas

  3. Air

  4. Carbon dioxide
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Among these only carbon dioxide is a compound.

Compound is a substance formed from two or more elements chemically bonded in a definite proportion.
Example- Carbon dioxide, water, glucose, etc.
In the given options,
A- the black residue that is left after charring sugar is carbon. Carbon is an element in pure state.
B- Nitrogen gas is a molecule as it is composed of only one element ie., Nitrogen so this can't be termed as a compound.
C- Air is a homogeneous mixture of different gases.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Gases mix at the molecular level. In an experiment, oxygen molecules were added to hydrogen molecules. This on burning became a substance that had both oxygen and hydrogen. What is this product?

  1. Mixture

  2. Compound

  3. Both a mixture as well as a compound

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

The product is water. It is formed after a chemical change (burning) and the properties of water is different from hydrogen and oxygen.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Which of the following do not show the properties of the constituents?

  1. Water

  2. Air

  3. Sugar solution

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water is a compound having hydrogen and oxygen atoms in the ratio of 2:1 and properties of water as chemical compound is different from the hydrogen and oxygen elements.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Two elements M and X have electronic configurations 2, 8, 3 and 2, 8, 6 respectively. Identify the correct formula of the compound formed.

  1. MX$ _2$
  2. M$ _2$X
  3. M$ _2$X$ _3$
  4. $M _3$X$ _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given that the electronic configuration of X = 2,8,3 and Y = 2,8,6. Thus the valencies they posses to attain noble gas configuration are; X = +3 and Y = -2. Therefore the formula of the compound formed can be written as; $M _{2}X _{3}$.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Water is a  _______ made up of hydrogen and oxygen combined in the ratio ______ by volume or _______ by mass.

  1. compound, 3:2, 1:1 respectively

  2. element, 1:2, 3:1 respectively

  3. compound, 2:1, 1:8 respectively

  4. molecule, 1:1, 1:16 respectively
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Water is a chemical compound made up of hydrogen and oxygen combined in the ratio $2:1$ by volume or $1:8$ by mass (2 g of hydrogen combines with 16 g of oxygen).