Tag: general introduction: importance and scope of chemistry

Questions Related to general introduction: importance and scope of chemistry

Which of the following is a compound?

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

  1. Carbon dioxide

  2. Iron

  3. Oxygen

  4. Air

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Correct Option: A
Explanation:
A compound is mixture of elements and molecules ,
Iron - element
Hydrogen - element
$CO _2$ - compound
Air - mixture
Oxygen - element

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

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

  1. Wilhelm Weins

  2. William J. Crooke

  3. Antonie L. Lavoisier

  4. Carl Bosch

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Correct Option: C
Explanation:

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

Which of the following is not a compound?

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

  1. Sugar

  2. Common Salt

  3. Diamond

  4. Plaster ofParis

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Correct Option: C
Explanation:

Diamond is the purest form of elemental carbon so it is not a compound.

Which one of the following is a compound?

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

  1. The black residue left when sugar is charred

  2. Nitrogen gas

  3. Air

  4. Carbon dioxide

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Correct Option: D
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.

What is the name of the element having chemical symbol I?

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

  1. Iodine

  2. Iron

  3. Indium

  4. Iridium

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Correct Option: A
Explanation:

The names and symbols of the element is as follows:

Indium ( In)
Iodine (I)
Iridium (Ir)
Iron (Fe)

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?

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

  1. Mixture

  2. Compound

  3. Both a mixture as well as a compound

  4. Solution

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Correct Option: B
Explanation:

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

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

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

  1. Water

  2. Air

  3. Sugar solution

  4. None of these

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Correct Option: A
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.

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

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

  1. MX$ _2$

  2. M$ _2$X

  3. M$ _2$X$ _3$

  4. $M _3$X$ _2$

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Correct Option: C
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; $M _{2}X _{3}$.

Can not be broken down chemically.

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

  1. Anions

  2. Cations

  3. Element

  4. Isotope

  5. Atom

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Correct Option: C
Explanation:

Element can not be broken down chemically. Elements are made of atoms of only one kind and that cannot be separated by ordinary chemical means into simpler substances.

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

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

  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

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Correct Option: C
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).