Class 10 Science Chapter 4 MCQ with Answers
Class 10 Science Chapter 4 MCQ Online tests practice with answers and explanations. Practice here to prepare for your school test and board papers. Questions are taken form NCERT Books and answers are also confined to NCERT textbooks only.
Q
Consider the following statements and choose the correct one(s):
[A]. Carbon and its compounds burn in air to give carbon dioxide gas which turns lime water milky.
[B]. The atomic number of carbon is 6 which means that a neutral atom of carbon contains 6 electrons.
[C]. All the living things, plants and animals, are made up of carbon based compounds which are called organic compounds.
[D]. All the above
Answer: Option D
Explanation:
Here, all these statements are correct. Hence, your answer will be option [D].
Q
Which of the following represents saponification reaction?
[A]. CH3COONa + NaOH + CaO → CH4 + Na2CO3
[B]. CH3COOH + C2H5OH + H2SO4 → CH3COOC2H5 +H2O
[C]. 2CH3COOH + 2Na → 2CH3COONa + H2
[D]. CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
Answer: Option D
Explanation:
In saponification reaction, when an ester is heated with sodium hydroxide solution, ester gets hydrolysed (breaks down) to form the parent alcohol and sodium salt of carboxylic acid.
Q
In the last year board examination, Rahul were asked a question where he had to choose the statement which was/were incorrect? Will you be able to answer this question?
[A]. If we burn graphite in oxygen, then only carbon dioxide gas is formed and nothing is left behind
[B]. Graphite does not conduct electricity.
[C]. The various physical forms in which an element can exist are called allotropes of the element.
[D]. Diamond is a colourless transparent substance having extraordinary brilliance.
Answer: Option B
Explanation:
The two common allotropes of carbon, diamond and graphite, have entirely different physical properties. For example, diamond is extremely hard whereas graphite is soft; diamond is a non-conductor of electricity whereas graphite is a good conductor of electricity.
Q
In a science quiz competition, Deepti asked a question where she had to choose the statement which was/were incorrect?
[A]. The diamond crystal is, therefore, made up of carbon atoms which are powerfully bonded to one another by a network of covalent bonds.
[B]. The melting point of diamond is also very high, being more than 3500°C.
[C]. Diamond is a conductor of electricity as there are ‘free electrons’ in a diamond crystal.
[D]. None of the above.
Answer: Option C
Explanation:
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.
Q
Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of
[A]. Helium
[B]. Neon
[C]. Argon
[D]. Krypton
Answer: Option B
Explanation:
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.
Q
Mineral acids are stronger acids than carboxylic acids because:
[A]. Mineral acids are completely ionized, carboxylic acids are partially ionized.
[B]. Carboxylic acids are completely ionized, mineral acids are partially ionized.
[C]. Mineral acids are completely ionized, carboxylic acids are completely ionized.
[D]. Mineral acids are partially ionized, Carboxylic acids are partially ionized.
Answer: Option A
Explanation:
Mineral acids are strong acids which ionise almost completely and carboxylic acids are weak acids which ionise only partially.
Q
Ethanol reacts with sodium and forms two products. These are
[A]. Sodium ethanoate and hydrogen
[B]. Sodium ethanoate and oxygen
[C]. Sodium ethoxide and hydrogen
[D]. Sodium ethoxide and oxygen
Answer: Option C
Explanation:
When a small piece of sodium reacts with ethanol, a colourless solution of sodium ethoxide, CH3CH2ONa is obtained. It also gives off bubbles of hydrogen gas. Sodium ethoxide is known as an alkoxide. You can easily understand by this equation: C2H5OH + 2Na → 2C2H5O-Na+ + H2
Q
Which of the following statement is or are incorrect?
[A]. The compounds of carbon are known as organic compounds.
[B]. Although oxides of carbon (like carbon monoxide and carbon dioxide), carbonates, hydrogen carbonates and carbides are also carbon compounds and they are considered to be organic compounds.
[C]. Most of the carbon compounds are non-conductors of electricity.
[D]. Carbon compounds (or organic compounds) are covalent compounds having low melting points and boiling points.
Answer: Option B
Explanation:
Though oxides of carbon (like carbon monoxide and carbon dioxide), carbonates, hydrogen carbonates and carbides are also carbon compounds but they are not considered to be organic compounds. This is because their properties are very different from those of the common organic compounds.
Q
In the last year board examination, Rahul were asked a question where he had to choose the statement which was/were incorrect? Will you be able to answer this question?
[A]. A compound made up of hydrogen and carbon only is called hydrocarbon.
[B]. The property of carbon element due to which its atoms can join with one another to form long carbon chains is called “carbonization”.
[C]. The study of carbon compounds (such as hydrocarbons and their derivatives) is called organic chemistry
[D]. None of the above.
Answer: Option B
Explanation:
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”).
Q
In the soap micelles:
[A]. The ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster.
[B]. Ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster.
[C]. Both ionic end and carbon chain are in the interior of the cluster.
[D]. Both ionic end and carbon chain are on the exterior of the cluster.
Answer: Option A
Explanation:
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.
Q
Chlorine reacts with saturated hydrocarbons at room temperature in the:
[A]. Absence of sunlight
[B]. Presence of sunlight
[C]. Presence of water
[D]. Presence of hydrochloric acid
Answer: Option B
Explanation:
Chlorine reacts with saturated hydrocarbons at room temperature in the presence of Sunlight to form alkyl chloride by displacement reaction.
Q
Which of the following statement is or are incorrect?
[A]. The general formula of alkynes is CH2n +2 where n is the number of carbon atoms in one molecule of the alkyne.
[B]. The unsaturated hydrocarbons are obtained mostly from petroleum by a process called cracking.
[C]. An unsaturated hydrocarbon in which the two carbon atoms are connected by a double bond is called an alkene.
[D]. The simplest alkene is ethene having the molecular formula C2H4.
Answer: Option A
Explanation:
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.
Q
Priya is writing some statements, choose the incorrect statement and help him:
[A]. The unsaturated hydrocarbons (having double bonds or triple bonds between the carbon atoms) are less reactive than saturated hydrocarbons.
[B]. The ethane molecule (C2H6) is made up of 2 carbon atoms and 6 hydrogen atoms.
[C]. The simplest alkyne is ethyne having the molecular formula C2H2.
[D]. An unsaturated hydrocarbon in which the two carbon atoms are connected by a triple bond is called an alkyne.
Answer: Option A
Explanation:
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.
Q
Bikash is doing his homework which is given by his teacher. Would you help him to choose the correct sentences?
[A]. The ethene molecule (C2H4) is made up of 2 carbon atoms and 4 hydrogen atoms.
[B]. Each carbon atom shares three electrons with three hydrogen atoms to form three carbon-hydrogen single covalent bonds.
[C]. In ethane, the two carbon atoms share one pair of electrons among themselves to form one carbon-carbon single covalent bond.
[D]. All the above.
Answer: Option D
Explanation:
Here, all these statements are correct. Hence, your answer will be option [D].
Q
Badal appeared in class test but he confused to know the correct statement. Would you help him to know that?
[A]. Ethane, ethene and ethyne are covalent molecules which are formed by the sharing of electrons between various atoms.
[B]. The ethyne molecule (C2H2) is made up of 2 carbon atoms and 2 hydrogen atoms.
[C]. The ethene molecule (C2H4) is made up of 2 carbon atoms and 4 hydrogen atoms.
[D]. All the above.
Answer: Option D
Explanation:
Here, all these statements are correct. Hence, your answer will be option [D].
Q
Consider the following statements and choose the correct one:
[A]. The group formed by the removal of one hydrogen atom from an alkane molecule is called an alkyl group.
[B]. An unsaturated hydrocarbon in which the two carbon atoms are connected by a triple bond is called an alkyne.
[C]. An unsaturated hydrocarbon in which the two carbon atoms are connected by a double bond is called an alkene.
[D]. All the above.
Answer: Option D
Explanation:
Here, all the statements are correct. Hence, your answer will be option [D].
Q
Which of the following statement is or are correct?
[A]. A saturated hydrocarbon containing single bonds is indicated by writing the word “ane” after the stem.
[B]. An unsaturated hydrocarbon containing a double bond is indicated by writing the word “ene” after the stem.
[C]. An unsaturated hydrocarbon containing a triple bond is indicated by writing the word “yne” after the stem.
[D]. All the above.
Answer: Option D
Explanation:
Here, all the statements are correct. Hence, your answer will be option [D].
Q
Read the following sentences carefully, and choose the incorrect one:
[A]. Normal-butane has a straight chain structure whereas iso-butane has a branched chain structure.
[B]. All the members of a homologous series can be represented by the different formula.
[C]. Isomerism is possible only with hydrocarbons having 4 or more carbon atoms.
[D]. The organic compounds having the same molecular formula but different structures are known as isomers.
Answer: Option B
Explanation:
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.
Q
A molecule of ammonia (NH3) has
[A]. Only single bonds
[B]. Only double bonds
[C]. Only triple bonds
[D]. Two double bonds and one single bond
Answer: Option A
Explanation:
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.
Q
Recently, in a science class test, you are asked a question where you have to say whether the statements are correct or not?
[A]. Any two adjacent homologous differ by 1 carbon atom and 2 hydrogen atoms in their molecular Formulae.
[B]. The difference in the molecular masses of any two adjacent homologous is 16 u.
[C]. All the compounds of a homologous series show similar chemical properties.
[D]. The members of a homologous series show a gradual change in their physical properties with increase in molecular mass.
Answer: Option B
Explanation:
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.
Q
Which of the following statements are usually correct for carbon compounds? These
[A]. are good conductors of electricity, have strong forces of attraction between their molecules.
[B]. are poor conductors of electricity, have strong forces of attraction between their molecules.
[C]. are good conductors of electricity, do not have strong forces of attraction between their molecule.
[D]. are poor conductors of electricity, do not have strong forces of attraction between their molecules.
Answer: Option D
Explanation:
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.
Q
Pooja is writing some statements but she confused to know whether the statements are correct or not? If you know the answer to this question, then tell her:
[A]. The alcohol group is made up of one oxygen atom and one hydrogen atom joined together.
[B]. That the elements chlorine, bromine and iodine are collectively known as halogens, so the chloro group, bromo group and iodol group are called halo groups.
[C]. An atom or ‘a group of atoms which makes a carbon compound (or organic compound) reactive and decides its properties (or functions) is called a functional group.
[D]. The carbon compounds (or organic compounds) containing carboxylic acid group (—COOH group) are called mineral acids.
Answer: Option D
Explanation:
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”.
Q
Carbon exists in the atmosphere in the form of:
[A]. Only carbon monoxide
[B]. Carbon monoxide in traces and carbon dioxide
[C]. Only Carbon dioxide
[D]. Coal
Answer: Option C
Explanation:
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.
Q
In a science quiz competition, Priyanka are asked a question where she had to choose the statement which was/were incorrect?
[A]. The IUPAC name of the compound CH3COCH2CH2CH3 is pentanone.
[B]. The IUPAC name of the compound CH3COCH2CH3 is butanone.
[C]. The IUPAC name of CH3COCH3 is propanone
[D]. The common name of pentanone is ethyl methyl ketone.
Answer: Option D
Explanation:
The common name of pentanone is methyl propyl ketone.
Q
In which of the following, 14 u, will be the differences in the molecular formulae and molecular masses:
[A]. CH3OH and C2H5OH
[B]. C2H5OH and C3H7OH
[C]. C3H7OH and C4H9OH
[D]. All of the above
Answer: Option D
Explanation:
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.
