Carbon And Its Compounds - MCQ Test (22-11-2017) - Class 10 MCQ

The functional group present in ethanol (C₂H₅OH) is the alcoholic group (-OH group). The hydroxyl group attached to a carbon atom is known as alcohol group.

The esters are found naturally in fruits like apples, pears, bananas, pineapples, and strawberries. Fruits exhibit their aroma due to the presence of esters. Hence, it is said that esters have a fruity smell. Esters are also present in vegetables. CH₃COOC₂H₅ is an ester.

The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. When acetic acid reacts with ethyl alcohol, an ester is formed along with water. Esterification is a reversible reaction. Concentrated sulphuric acid acts as a dehydrating agent and absorbs water from the product mixture so that the reaction proceeds in the forward direction. CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

A, B and D are isomers of hexane - they have the same molecular formula but different structural formulae. C represents an isomer of pentane C₅H₁₂

The next homologue of C₅H₁₁COOH (Pentanoic acid) is C₆H₁₃COOH (Hexanoic acid). Two adjacent homologues in a series differ by 1 carbon atom and 2 hydrogen atoms i.e. by a CH₂ group.

A brisk effervescence of carbon dioxide gas will be observed when ethanoic acid reacts with solid sodium bicarbonate. This reaction is used is a test for ethanoic acid.

CH₃COOH + NAHCO₃ → CH₃COONa + H₂O + CO₂

Acetic acid is a weak acid (an organic acid). It does not ionise completely when dissolved in water.

B and D are unsaturated hydrocarbons (they contain double or triple bonds between two carbon atoms). B is ethyne (an alkyne). D is iso-butene (2-methyl propene)
A and C are saturated hydrocarbons (they contain only single bonds between the carbon atoms).

Ethanol (C₂H₅OH) is used for antifreeze mixture. Antifreeze is an additive which lowers the freezing point of a water-based liquid. At room temperature, ethanol is a polar solvent and is used as antifreeze.

Soap is basic in nature. Acid dyes are used to dye protein fibers such as silk, wool, angora, mohair, feathers, etc. Hence, soap doesn’t work well with woolen garments. The soap gets neutralised by the acidic dyes.

All soaps are biodegradable i.e. they can be decomposed by micro-organsims like the bacteria. Branched chain synthetic detergents are far less degradable than unbranched detergents.

Carbon compounds are usually poor conductors of heat and electricity. Carbon compounds are covalent compounds that have been formed by the sharing of electrons. They do not have strong forces of attraction between their molecules. They have weak interactions between their molecules. This leads to low melting points and boiling points.

3 structural isomers are possible for pentane (C₅H₁₂). These are n-pentane, iso-pentane and neo-pentane.

Invertase helps in breaking sucrose into its component parts - glucose and fructose. Zymase converts starch into glucose. Diastase transforms starch into maltose and after that it converts it into glucose. Maltase is an enzyme that can break down disaccharide maltose.

Activated charcoal is activated carbon. It is a form of carbon processed to have small, low-volume pores that increases the surface area available for adsorption or chemical reactions. Activated charcoal is used as a decolorizing agent in the sugar industry.

Ethanol and propanol are alcohols and contain the functional group -OH. Ethanol is C₂H₅OH and propanol is C₃H₇OH. Ethanoic acid contains the carboxylic group (-COOH).

A soap molecule is said to have a tadpole structure. It consists of 2 parts - a long hydrocarbon chain which is water-repellent (hydrophobic) and an ionic part which is water-attracting (hydrophillic) due to the polar nature of water molecules.

The given reaction is an example of addition reaction. In this reaction, a bromine atom adds to each carbon atom of ethene. The double bond in ethene is broken and the hydrocarbon becomes saturated.

Carbon can exist in three solid forms (Diamond, Graphite, Fullerenes) called allotropes. C₆₀ and C₇₀ are members of Fullerenes (Allotropes of carbon). Buckminsterfullerene contains cluster of 60 carbon atoms joined together to form spherical molecules.

Water molecule is a covalent compound formed by the sharing of electrons between the hydrogen atoms and the oxygen atom. Metals like Na and Mg are electropositive in nature and form ionic compounds with electronegative non-metals.

Soap is made by heating animal oil or vegetable oil with concentrated sodium hydroxide solution. Castor oil and NaOH are the ingredients for making soap. Similarly, cotton seed oil and KOH, and mustard oil and NaOH are also the ingredients for making soap.

C₁₀H₂₁COOH : Hendecanoic acid (also known as undecanoic acid, undecylenic acid and undecylic acid) is a naturally occurring carboxylic acid. It has a melting point in the range 28 - 31 ^oC. It is a low melting solid.
​C₁₉H₃₉COOH : Arachidic acid or eicosanoic acid is a white crystalline solid at room temperature (25 ^oC). It has a melting point in the range 74 - 76 ^oC

Solubility of alcohols in water decreases with increasing molecular weight. The first three alcohols (methanol, ethanol and propanol) are completely miscible. Each alcohol consists of a carbon chain (always non-polar) and a OH group (which is polar). The solubility of alcohols starts to decrease with butanol. Alcohols are considered immiscible after heptanol. 

Boiling point of alcohols increases with increasing molecular weight. The boiling point of alcohols increases as the length of the hydrocarbon chain increases.

Reduction is the process of removal of oxygen and/or addition of hydrogen.

Freezing point of ethanoic acid is 17 °C (290 K). When ethanoic acid (acetic acid) is cooled, it freezes to form a colourless, ice-like solid. The solid looks like a glacier and hence pure ethanoic acid is also called glacial ethanoic acid (or glacial acetic acid).

Soaps are basic in nature. Soaps are sodium or potassium salts of long chain fatty acids. When triglycerides in fat/oil react with aqueous NaOH or KOH, they are converted into soap and glycerol. This is called alkaline hydrolysis of esters. E.g. C₁₇H₃₁COONa (Sodium stearate) is a soap. Scum is produced when the soap reacts with calcium and/or magnesium ions present in hard water.

Ethanol (C₂H₅OHC₂H₅OH) is a cleaner fuel. It is used as a fuel in cars along with petrol. It is also used as a fuel in spirit lamps.

Oxidation of an aldehyde (-CHO group) leads to the formation a carboxylic acid (-COOH group). A carboxylic acid turns blue litmus red. 

Oxyacetylene flame is used for welding purposes. The oxyacetylene welding process uses a combination of oxygen and acetylene (C₂H₂) gas to provide a high temperature flame. It is commonly used to join mild steel permanently.

Ethyne (C₂H₂) reacts with HCl in the presence of HgCl₂ to from vinyl chloride or chloro ethane H₂C=CHCl. This colorless compound is an important industrial chemical. It is chiefly used to produce polyvinyl chloride (PVC).

Hardness of water is caused by magnesium and calcium salts. Calcium and magnesium dissolved in water are the two most common minerals that make water hard. Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate).