Use of Chemistry

I. Introduction

 A. Positive Uses of Chemistry

 B. Negative Uses of Chemistry

II. Positive Uses of Chemistry

 A. Medicine

 1. Drug development

 2. Diagnostic tests

 3. Treatment of diseases

 B. Agriculture

 1. Fertilizers

 2. Herbicides

 3. Pesticides

III. Negative Uses of Chemistry

 A. Pollution

 1. Air pollution

 2. Water pollution

 3. Land pollution

 B. Health Effects

 1. Respiratory problems

 2. Cancer

 3. Reproductive health issues

Here are some multiple-choice questions related to matter:

1. Which of the following is NOT a state of matter?

a) Solid

b) Liquid

c) Gas

d) Plasma

e) Energy

Answer: e) Energy

2. What is the process by which a solid changes directly to a gas?

a) Condensation

b) Melting

c) Sublimation

d) Freezing

Answer: c) Sublimation

3. Which of the following is an example of a homogeneous mixture?

a) Salad

b) Orange juice with pulp

c) Saltwater

d) Sand and water

e) Trail mix

Answer: c) Saltwater

4. What is the SI unit of mass?

a) Gram

b) Pound

c) Ounce

d) Kilogram

e) Newton

Answer: d) Kilogram

5. Which of the following statements is true about atoms?

a) Atoms are the smallest unit of matter that can exist on their own.

b) Atoms are made up of electrons and protons.

c) Atoms of different elements have different numbers of protons.

d) All of the above.

Answer: d) All of the above.

Class 7 chemistry physical and chemical change

Tick (✔) The correct choice amongest the following 1. Sublimation of iodine is a : (a) Chemical change (b) Physical change (c) Periodic change (d) Irreversible change 1 Mark(s) 2. When magnesium ribbon is burnt, heat and light are produced. It is an example of : (a) Chemical change (b) Physical and irreversible change (c) Chemical and exothermic change (d) Chemical and endothermic change 1 Mark(s) 3. Powdering of sugar is : (a) Chemical and irreversible change (b) Physical change (c) Reversible change (d) Irreversible change 1 Mark(s) 4. Making ice from water is an example of : (a) Man-made change (b) Chemical change (c) Sublimation (d) Undesirable change 1 Mark(s) 5. Melting of butter is not a : (a) Fast change (b) Desirable change (c) Reversible change (d) Permanent change 1 Mark(s)

Answer

Write True False for each statement, Rewrite the false statements 1. In an exothermic reaction, heat is given out. 1 Mark(s) 2. In a chemical reaction no new substance is formed. 1 Mark(s) 3. Reaction of zinc pieces with hydrochloric acid is an exothermic reaction. 1 Mark(s) 4. Glowing of an electric bulb is a physical change. 1 Mark(s) 5. Breaking of a glass tumbler is a reversible change. 1 Mark(s) 6. Burning of wood is a chemical change. 1 Mark(s)

Answer

Select the Odd and Out Giving reason 1. Burning of wood, rusting of iron, souring of milk, freezing of water. 1 Mark(s) 2. Freezing of water, magnetising an iron nail, breaking of chalk stick. 1 Mark(s) 3. Rusting, burning, combustion, melting. 1 Mark(s)

Answer

Class 7 chemistry Matter around us

Tick (✔) The correct choice amongest the following

1. Which of the following is not a matter ? (a) Shadow (b) Chair (c) Toast (d) Juice

Answer

1 Mark(s)

2. What can be poured from one vessel to another ? (a) Solids (b) Fluids (c) Air (d) Water

Answer

1 Mark(s)

3. Maximum intermolecular spaces are present between : (a) Solids (b) Liquids (c) Gases (d) All of the above

Answer

1 Mark(s)

4. Physical states of matter can be interchanged by : (a) Heating (b) Cooling (c) Heating or cooling (d) None of the above

Answer

1 Mark(s)

5. Mixture of two phases : (a) Gas (b) Solid (c) Liquid (d) Vapour

Answer

1 Mark(s)

Write True False for each statement, Rewrite the false statements

1. Solids have high densities, are rigid and hard.

Answer

1 Mark(s)

2. Gaseous state have least kinetic energy.

Answer

1 Mark(s)

3. Love, hate, shadow cannot be classified as matter.

Answer

1 Mark(s)

4. The process in which solid gets converted to liquid state is known as sublimation.

Answer

1 Mark(s)

5. Naphthalene and camphor are sublimable compounds.

Answer

1 Mark(s)

Select the Odd and Out Giving reason

1. Melting, freezing, evaporation, sublimation

Answer

1 Mark(s)

2. Napthalene, camphor, iodine, common salt

Answer

1 Mark(s)

3. Water, juice, oil, ice-cream

Answer

1 Mark(s)