Class 10 Science Chapter 4 MCQ

A carbon atom has 4 electrons in its outermost shell, so it requires 4 more electrons to achieve the stable, 8-electron inert gas electron arrangement, which it gets by sharing. Since one carbon atom requires 4 electrons to achieve the eight-electron inert gas structure, therefore, the valency of carbon is 4. That is, carbon is tetravalent (tetra = four; valent = valency).

The covalent bonds between the various carbon atoms are very strong and do not break easily. The reason for the formation of strong bonds by the carbon atoms is their small size. Due to the small size of carbon atoms, their nuclei hold the shared pairs of electrons between atoms strongly, leading to the formation of strong covalent bonds.

Functional group present in CH3 – CH2 – CHO is aldehyde. It is propanal containing 3 carbon atom in which “propane” represents 3 carbon atoms while “al” represents aldehyde group. So, propane + al = propanal.

Because successive members of a homologous series differ by -CH2 unit. You can easily understand by this equation: (C3H8) + (CH2) = C4H10. Thus, C4H10 is the next members of this series. So, homologous series of alkanes is: Methane CH4, Ethane C2H6, Propane C3H8, Butane C4H10. So, C4H8 does not belong to the homologous series. Note: Homologous series is a group of organic compounds having similar structures and similar chemical properties in which a successive compound differs by CH2 group.

Here, all these statements are correct. Hence, your answer will be option [D].

Mineral acids are strong acids which ionise almost completely and carboxylic acids are weak acids which ionise only partially.

Due to its softness, powdered graphite is used as a lubricant for the fast moving parts of machinery. Since graphite is non-volatile, it can be used for lubricating those machine parts which operate at very high temperatures (where ordinary oil lubricants cannot be used). Graphite can be used as a dry lubricant in the form of graphite powder or mixed with petroleum jelly to form graphite grease. Graphite powder can also be mixed with lubricant oils.

Pentane has 16 covalent bonds.

A “spherical aggregate of soap molecules” in a soap solution in water is called a “micelle”. In a soap micelle, the soap molecules are arranged readily with hydrocarbon ends directed towards the centre and ionic ends directed outwards.

The general formula of saturated hydrocarbons or alkanes is CnH2n + 2 where n is the number of carbon atoms in one molecule of the alkane. You can easily understand by this example: Example: If an alkane has 2 carbon atoms in its molecule, then n = 2, and its molecular formula will be C2H2×2+2 or C2H6

A hydrocarbon in which the two carbon atoms are connected by a “double bond” or a “triple Bond” is called an unsaturated hydrocarbon. Propene, CH3CH = CH2 and Propyne CH3 –C ≡ CH both have double and triple bonds, respectively hence unsaturated. Propane and chloropropane are saturated hydrocarbons which contain only single bonds.

The unsaturated hydrocarbons (having double bonds or triple bonds between the carbon atoms) are more reactive than saturated hydrocarbons. In other words, alkenes and alkynes are chemically more reactive than alkanes.

Here, all these statements are correct. Hence, your answer will be option [D].

Butanol, CH3 – CH2 – CH2 – CH2 – OH. The alcohols are organic compounds. They all contain the functional group –OH. This group possess the properties of alcohols. The names of alcohols end with -ol – e.g., ethanol, butanol.

Oils are unsaturated compounds containing double bonds. Addition reaction are characteristic property of unsaturated hydrocarbons. The given reaction is an example of addition reaction. You can easily understand by this: Edible oils + H2 + Ni or Pd + Heat → Fats (ghee)

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Buckminsterfullerene is an allotrope of carbon containing clusters of 60 carbon atoms joined together to form a spherical molecule. Its formula is C60. It is a dark solid at room temperature and as compared to another allotrope from of carbon (as diamond and graphite), it is neither very hard nor soft.

It is the characteristics of a “Homologous Series” is that all the members of a homologous series can be represented by the same general formula. For example, all the members of the alkane series can be represented by the general formula CnH2n+2.

It is the characteristics of a Homologous Series is that the difference in the molecular masses of any two adjacent homologous is 14 u. For example, the molecular mass of methane (CH4) is 16 u, and that of its next higher homologue ethane (C2H6) is 30 u. So, the difference in the molecular masses of ethane and methane is 30 – 16 = 14 u.

Carbon mainly forms covalent compounds, which due to the absence of free ions, are generally poor conductors of electricity. Also, the forces of attraction in between their molecules are weak. Note: Atomic number of carbon is 6. So, its electronic configuration is 2, 4. It can achieve the inert gas electron arrangement only by the sharing of electrons.

The carbon compounds (or organic compounds) containing carboxylic acid group (—COOH group) are called carboxylic acids. Carboxylic acids are commonly known as organic acids. Another name for carboxylic acids is alkanoic acids. The carboxylic acids or organic acids are made up of three elements: carbon, hydrogen and oxygen. The simplest carboxylic acid (or organic acid) is formic acid, HCOOH, which is also known as “Methanoic acid”.

Carbon exist in the atmosphere in the form of carbon dioxide gas (CO2) in air (only 0.03%). Carbon also occurs in the earth’s crust in the form of minerals like carbonates. It also occurs in the form of fossil fuels, organic compounds, wood, cotton and wool etc.

Here, all these statements are correct. Hence, your answer will be option [D].

Here, 14 u, will be the differences in the molecular formulae and molecular masses in all these statements. Hence, your answer will be option [D]. You can easily understand by this: In option [A]: The difference in the molecular formulae of CH3OH and C2H5OH is CH2. The difference in the molecular masses of CH3OH and C2H5OH is 46 – 32 = 14 u. In option [B]: The difference in the molecular formulae of C2H5OH and C3H7OH is CH2. And the difference in the molecular masses of C2H5OH and C3H7OH is 60 – 46 = 14 u. In option [C]: The difference in the molecular formulae of C3H7OH and C4H9OH is CH2. And the difference in the molecular masses of C3H7OH and C4H9OH is 74 – 60 = 14 u.