Allied solutions simplified middle school chemistry class 8 Solutions for Chapter 9 carbon and its compounds

Q1) Differentiate between two branches of chemistry - organic chemistry & inorganic chemistry with suitable examples.

Q2) State how carbon occurs in the free state and in the combined state.

Q3) Define the term ‘allotropy’. Give a reason why carbon exhibits allotropy.

Q4) Name two crystalline and four amorphous allotropes of carbon.

Q5) Compare the structure of the crystal of diamond & graphite with special reference to the reason for diamond being the hardest natural substance while graphite one of the softest. Compare the electrical & thermal conductivity of the two crystalline allotropes of carbon.

Q6) With reference to the structure of the two crystalline allotropes of carbon, state why diamond is inert or unreactive while graphite is comparably more reactive.

Q7) State the reasons for

(a) Use of diamond - as an item of jewellery

(b) Use of graphite -

(i) as a lubricant for heated machine parts

(ii) as a lining for crucibles used in manufacture of high grade steel

(iii) as an electrode in electroplating

Q8) State in brief the transformation of vegetable matter to different types of coal varying in carbon content. State two uses of each -

(a) Coal

(b) Coke

(c) Lampblack or soot

Q9) ‘Wood charcoal - an amorphous allotrope of carbon reduces heated metallic oxides to metals’. Give a balanced equation to support the statement.

Q10) Carbon dioxide occurs both in the free state and in the combined state. State three methods of how carbon dioxide is added to the atmosphere.

Q11) In the laboratory preparation of carbon dioxide by action of a dilute acid on a metallic carbonate give - (a) A balanced equation for the preparation (b) A reason for (i) use of a washer bottle containing concentrated H_2SO_4 in the preparation (ii) Not collecting the prepared gas over water (iii) Not using dilute sulphuric acid as a reactant in the preparation.

Q12) How would you prove experimentally that

(a) Carbon dioxide does not support combustion

(b) Is slightly acidic in nature.

Q13) Starting from carbon dioxide how would you obtain -

(a) A weak acid

(b) A fertilizer

(c) A highly poisonous gas

(d) Black particles of carbon

[[Give balanced equations for the same]]

Q14) State how you would convert carbon dioxide to a metallic carbonate using a basic oxide e.g. sodium oxide [[give a balanced equation]]

Q15) ‘When carbon dioxide is bubbled into lime water, the limewater turns milky and when bubbled in excess the milkiness disappears’. Give a balanced equation to support the statement.

Q16) Explain the term ‘dry ice’. State its application. Give three reasons why carbon dioxide finds application in fire extinguishers.

Q17) Using a magnesium ribbon, how would you prove that a given gas jar contains carbon dioxide.

Q18) State the function of concentrated sulphuric acid in the laboratory preparation of carbon monoxide from oxalic acid.

Q19) Give reasons why carbon monoxide is considered a highly poisonous gas. State why it is dangerous.

1. To sleep in a closed room with a fuel burning

2. To be in the vicinity of smokers.

Q20) Convert carbon monoxide to carbon dioxide using two methods.

Q21) State how carbon monoxide finds application in

1. The metallurgy of iron

2. Preparation of an alcohol

[[Give balanced equations for the same]]

Q1) Name the following:

1. A crystalline allotrope of carbon built up from a hexagonal unit.

2. An allotrope of carbon used for the manufacture of coke.

3. An amorphous allotrope of carbon which floats on water.

4. An acid formed when carbon dioxide is dissolved in water under pressure.

5. The gaseous product obtained when carbon monoxide is passed over heated iron [II] oxide.

Q2) Select the correct answer from A,B,C,D & E for each statement given below:

A: Anthracite B: Diamond C: Carbogen D: Urea E: Lampblack

1. An allotrope of carbon used as a tip for deep boring drills.

2. The type of coal with the highest carbon content.

3. An allotrope of carbon obtained by burning kerosene oil in a limited supply of air.

4. A nitrogenous fertilizer obtained from carbon dioxide.

5. A compound which finds use for a victim of carbon monoxide poisoning.

Q3) Give a balanced equation for the following conversions: [In one or two steps]

1. Coke to water gas

2. Calcium bicarbonate to calcium nitrate using a dilute acid.

3. Lime water to calcium bicarbonate.

4. Carbon dioxide to carbon

5. A metallic oxide to calcium carbonate.

Q4) Complete the statement by filling in the blanks with the correct word from the bracket.

1. The crystal of ______ [[diamond/graphite]] is opaque to light and is a good conductor of heat.

2. A graphite-clay mixture baked at high temperature is used in making ______ [[lubricants/refractory cruscibles]]

3. Adsorption capacity of wood charcoal is increased by passing ____ [[carbon dioxide/steam]] over wood charcoal, at high temperature.

4. ______ [[organic/inorganic]] chemistry is the chemistry of carbon compounds mainly of 'carbon', 'hydrogen' & 'oxygen'.

5. Sodium oxide combines with carbon dioxide to give _____ [[sodium carbonate/sodium bicarbonate]]

Q5) Give reasons for the following:

1. Diamond & graphite are allotropic modifications of carbon.

2. It is dangerous to stand behind a running engine of a vehicle.

3. Both CO_2 & SO_2 turn lime water milky. Moist potassium permanganate paper helps in distinguishing the two gases.

4. Carbon monoxide and not carbon dioxide is highly poisonous gas.

5. Lime water finds application for testing both carbon dioxide & carbon monoxide gas individually.