Class 10 Science Chapter 4 MCQ

The general formula of alkyne is CnH2n-2 where, n is the number of carbon atoms. The first member of Alkyne homologous series is ethyne C2H2.

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).

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.

A carbon atom has 4 valence electrons in it. Now, in a diamond crystal, each carbon atom is linked to four other carbon atoms by covalent bonds, and hence all the 4 valence electrons of each carbon atom are used up in forming the bonds. Since there are ‘no free electrons’ in a diamond crystal, it does not conduct electricity.

Electronic configuration of carbon (C) = 2, 4 when it forms four covalent bonds by sharing its four valence electrons with hydrogen, it forms CH4 molecule. You can easily understand by this: Electronic configuration of C in CH4 = 2, 8. Atomic number of Ne is 10. Its electronic configuration is (K2), (L8). Therefore, after the formation of four bonds carbon attains the electronic configuration of neon.

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

A 5% to 8% solution of Acetic acid in water is called vinegar.

The property of carbon element due to which its atoms can join with one another to form long carbon chains is called catenation. So, it is the property of “catenation” of carbon element which is responsible for a very large number of organic compounds (catenation means “self-linking”).

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

Chlorine reacts with saturated hydrocarbons at room temperature in the presence of Sunlight to form alkyl chloride by displacement reaction.

The general formula of alkynes is CnH2n – 2 where n is the number of carbon atoms in one molecule of the alkyne. You can easily understand by this example: Example, If an alkyne has 3 carbon atoms in its molecule, then n = 3, and its molecular formula will be C3H2×3–2 or C3H4.

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.

A soap molecule is made up of two parts: a long hydrocarbon part and a short ionic part -COO-Na+ group. The long hydrocarbon chain is hydrophobic (water repelling) and ionic portion is hydrophilic (water attracting).

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

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.

A molecule of ammonia (NH3) has only single bonds and these are covalent bonds. Note: Atomic number of N is 7. Its electronic configuration is 2, 5 so it needs 3 more electrons to complete its “Octet”. It gains 3 electrons each from 3 hydrogen atoms. Also, N has one lone pair of electrons. The pair of electrons on the nitrogen atom in NH3 molecule which is not involved in bond formation is called lone pair.

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.

The common name of pentanone is methyl propyl ketone.

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