For the symbol H
[question] Question. For the symbol H, D and T tabulate three sub-atomic particles found in each of them. [/question] [solution] Solution: [/solution]...
Read More →While cooking,
[question] Question. While cooking, if the bottom of the vessel is getting blackened on the outside, it means that (1) the food is not cooked completely (2) the fuel is not burning completely (3) the fuel is wet (4) the fuel is burning completely [/question] [solution] solution: (2) the fuel is not burning completely [/solution]...
Read More →Write the electronic configuration
[question] Question. Write the electronic configuration of any one pair of isotopes and isobars. [/question] [solution] Solution: ${ }_{6}^{12} \mathrm{C}$ and ${ }_{6}^{14} \mathrm{C}$ are isotopes, have the same electronic configuration as $(2,4)$. ${ }_{20}^{40} \mathrm{Ca}$ and ${ }_{18}^{40} \mathrm{Ar}$ are isobars. They have different electronic configuration as given below: ${ }_{20}^{40} \mathrm{Ca}-2,8,8,2$ ${ }_{18}^{40} \mathrm{Ar}-2,8,8$ [/solution]...
Read More →Butanone is a four-carbon compound
[question] Question. Butanone is a four-carbon compound with the functional group, (1) Carboxylic acid (2) aldehyde (3) ketone (4) alcohol [/question] [solution] solution: (3) ketone [/solution]...
Read More →Ethane, with the molecula
[question] Question. Ethane, with the molecular formula $\mathrm{C}_{2} \mathrm{H}_{6}$ has (1) 6 covalent bonds (2) 7 covalent bonds (3) 8 covalent bonds (4) 9 covalent bonds [/question] [solution] solution: (2) 7 covalent bonds [/solution]...
Read More →Oxygen atom has 8 electrons,
[question] Question. Oxygen atom has 8 electrons, 8 protons and 8 neutrons whereas sulphur atom has 16 electrons, 16 protons and 16 neutrons. Find out the mass number of oxygen and sulphur atoms. [/question] [solution] Solution: Mass number of oxygen = Number of protons + Number of neutrons = 8 + 8 =16 Mass number of sulphur = Number of protons + Number of neutrons = 16 +16 = 32 [/solution]...
Read More →If number of electrons in an atom is 8 and number of protons is also 8,
[question] Question. If number of electrons in an atom is 8 and number of protons is also 8, then (i) what is the atomic number of the atom and (ii) what is the charge on the atom? [/question] [solution] Solution: (i) Atomic number = number of protons.= 8. (ii) Number of electrons (-ve) = number of protons (+ve) , therefore, the charge on the atom is 0....
Read More →The following real numbers have decimal expansions as given below. In each case, decide
[question] Question. The following real numbers have decimal expansions as given below. In each case, decide whether they are rational, or not. If they are rational, and of the form $\frac{\mathbf{P}}{\mathbf{q}}$, what can you say about the prime factors of $\mathrm{g}$ ? (i) $43.123456789$ (ii) $0.120120012000120000 \ldots$ (iii) $43 . \overline{23456789}$ [/question] [solution] Solution: (i) $43.123456789$ Since, the decimal expansion terminates, so the given real number is rational and there...
Read More →How will you find the valency of chlorine, sulphur and magnesium?
[question] Question. How will you find the valency of chlorine, sulphur and magnesium? [/question] [solution] Solution: (i) Atomic number of chlorine $=17$ Thus, outermost shell has 7 electrons. It can easily complete its octet by gaining one electron. Hence, its valency = 1. (ii) Atomic number of sulphur = 16 Thus, outermost shell has 6 electrons. Hence, valency = 8 – 6 = 2 (iii) Atomic number of magnesium = 12\ Thus, outermost shell has 2 electrons. It can easily complete its octet by loosing ...
Read More →Would you be able to check if water is hard by
[question] Question. Would you be able to check if water is hard by using a detergents ? [/question] [solution] solution: No, because no scum formation takes place when detergent is added to hard water. [/solution]...
Read More →What are oxidising agents?
[question] Question. What are oxidising agents? [/question] [solution] solution: Oxidising agents are substances which are capable of adding oxygen to other substances, for examples, both alkaline potassium permanganate and acidified potassium dichromate can convert ethanol to ethanoic acid. e.g. alkaline potassium permanganate $\mathrm{KMnO}_{4}$, acidified potassium dichromate $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$. [/solution]...
Read More →Write down the decimal expansions of those rational numbers in Question
[question] Question. Write down the decimal expansions of those rational numbers in Question 1 above which have terminating decimal expansions. [/question] [solution] Solution: (i) $\frac{13}{3125}=\frac{13}{5^{5}}=\frac{13 \times 2^{5}}{5^{5} \times 2^{5}}=\frac{416}{10^{5}}=0.00416$ (ii) $\frac{17}{8}=\frac{17}{2^{3}}$$=\frac{17 \times 5^{3}}{\mathbf{2}^{3} \times \mathbf{5}^{3}}=\frac{\mathbf{1 7} \times \mathbf{5}^{3}}{\mathbf{1 0}^{3}}=\frac{\mathbf{2 1 2 5}}{\mathbf{1 0}^{3}}=2.125$ (iv) $...
Read More →If K and L shells of an atom are full,
[question] Question. If K and L shells of an atom are full, then what would be the total number of electrons in the atom? [question] [solution] Solution: The maximum number of electrons that can occupy K and L-shells of an atom are 2 and 8 respectively. Therefore, if K and L-shells of an atom are full, then the total number of electrons in the atom would be (2 + 8) = 10 electrons. [/solution]...
Read More →How would you distinguish experimentally
[question] Question. How would you distinguish experimentally between an alcohol and a carboxylic acid? [/question] [solution] solution: Sodium bicarbonate test Take a small amount of each compound in a test tube and add to it an aqueous solution of $\mathrm{NaHCO}_{3}$. The compound which produces brisk effervescence due to the evolution of $\mathrm{CO}_{2}$ must be a carboxylic acid [/solution]...
Read More →A mixture of oxygen and ethyne is burnt for welding.
[question] Question. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used? [/question] [solution] solution: Ethyne is an unsaturated hydrocarbon, therefore, combustion of ethane in air produces a yellow flame with black smoke due to the presence of unburnt carbon in it. Due to this incomplete combustion heat produced is also low and a high temperature usually needed for welding cannot be attained. That is why mixture of ethyne & oxygen is ...
Read More →Write the distribution of electrons in carbon and sodium atoms?
[question] Question. Write the distribution of electrons in carbon and sodium atoms? [/question] [solution] Solution: The total number of electrons in a carbon atom is 6. The distribution of electrons in carbon atom is given by: First orbit or K-shell = 2 electrons Second orbit or L-shell = 4 electrons Or, we can write the distribution of electrons in a carbon atom as 2, 4. The total number of electrons in a sodium atom is 11. The distribution of electrons in sodium atom is given by: First orbit...
Read More →Why is the conversion of ethanol to ethanoic
[question] Question. Why is the conversion of ethanol to ethanoic acid an oxidation reaction? [/question] [solution] solution: The reaction showing the conversion of ethanol to ethanoic acid can be shown as : A molecule of ethanol contains one oxygen alone while that of ethanoic acid contains two oxygen atoms. Since oxidation involves addition of oxygen therefore, conversion of ethanol to ethanoic acid is an oxidation reaction. Alternatively, a molecule of ethanol contains six hydrogen atoms whi...
Read More →Helium atom has an atomic mass of 4 u
[question] Question. Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have? [/question] [solution] Solution: The mass of an atom is given by the sum of the masses of protons and neutrons present in the nucleus. Since helium atom has an atomic mass of 4u and it has two protons, the protons contribute 2u to atomic mass. Hence, it must contain 2 neutrons as each neutron contributes 1u to the nucleus. [/solution]...
Read More →How would you name the following compounds?
[question] Question. How would you name the following compounds? (i) $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{Br}$ [/question] [solution] solution: (i) Bromoethane (ii) Methanal (iii) Hexyne [/solution]...
Read More →Name the three sub-atomic particles of an atom
[question] Question. Name the three sub-atomic particles of an atom. [/question] [solution] Solution: The three sub-atomic particles of an atom are: Protons, Electrons and Neutrons. [/solution]...
Read More →Without actually performing the long division, state whether the following rational numbers expansion.
[question] Question. Without actually performing the long division, state whether the following rational numbers expansion. will have a terminating decimal expansion or a non-terminating repeating decimal (i) $\frac{13}{3125}$ (ii) $\frac{17}{8}$ (iii) $\frac{64}{455}$ (iv) $\frac{15}{1600}$ (v) $\frac{29}{343}$ (vi) $\frac{23}{2^{3} 5^{2}}$ (vii) $\frac{129}{2^{2} 5^{7} 7^{5}}$ (viii) $\frac{6}{15}$ (ix) $\frac{35}{50}$ (x) $\frac{77}{210}$ [/question] [solution] Solution: (i) $\frac{13}{3125}=...
Read More →Draw the possible structural isomers
[question] Question. Draw the possible structural isomers for bromopentane. [/question] [solution] solution: (i) Bromopentane $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{Br}$ [/solution]...
Read More →What do you think would be the observation
[question] Question. What do you think would be the observation if the $\alpha$-particle scattering experiment is carried out using a foil of a metal other than gold? [/question] [solution] Solution: If $\alpha$-particle scattering experiment is carried out using a foil of any metal as thin as gold foil used by Rutherford, there would be no change in observations. But since other metals are not so malleable. So, such a thin foil is difficult to obtain. If we use a thick foil, then more $\alpha-$...
Read More →On the basis of Rutherford’s model of an atom,
[question] Question. On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom? [question] [solution] Solution: Protons which are positively-charged particles are present in the nucleus of an atom. [/solution]...
Read More →On the basis of Thomson’s model of an atom,
[question] Question. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole. [/question] [solution] Solution: J.J. Thomson, the discoverer of the electron believed that the atom is a uniform sphere of positive charge with electron embedded in it. This model explained the electrical neutrality of atom, but it failed to explain how these fundamental particles were arranged in the atom. [/solution]...
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