Which of the following can undergo
Question: Which of the following can undergo a chemical reaction ? (a)MgSO4+ Zn (b)ZnSO4+ Fe (c)CaSO4+ Pb (d)CuSO4+ Al Solution: (d).Only Al can displace Cu from CuSO4solution since it is placed above Cu in the activity series....
Read More →Fill in the blanks.
Question: Fill in the blanks. (i)x2 18x+ 81 = (......) (ii) 4 36x2= (......)(......)(......) (iii)x2 14x+ 13 = (......)(......) (iv) 9z2x2 4y2+ 4xy= (......)(......) (v)abcabc+ 1 = (......)(......) Solution: (i) $(x-9)^{2}$ $x^{2}-18 x+81$ $=x^{2}-2 \times x \times 9+9^{2}$ $=(x-9)^{2}$ (ii) (4) $(1-3 x)(1+3 x)$ $4-36 x^{2}$ $=4\left(1-9 x^{2}\right)$ $=4\left(1^{2}-(3 x)^{2}\right)$ $=(4)(1-3 x)(1+3 x)$ (iii) $(x-13)(x-1)$ $x^{2}-14 x+13$ $=x^{2}-13 x-x+13$ $=x(x-13)-1(x-13)$ $=(x-13)(x-1)$ (iv...
Read More →Which of the following non-metals is a liquid ?
Question: Which of the following non-metals is a liquid ? (a)Carbon (b)Bromine (c)Iodine (d)Sulphur Solution: (b).Non-metal bromine is a liquid but in the molecular form (Br2)....
Read More →Define a function as a correspondence between two sets.
Question: Define a function as a correspondence between two sets. Solution: Function as a correspondence between two sets: Let A and B be two non empty sets. Then, a function f from set A to set B is a correspondence (rule) which associates elements of set A to elements of set B such that: (i) all elements of set A are associated with an element in set B. (ii) an element of set A is associated with a unique element in set B....
Read More →Electrical wires have a coating
Question: Electrical wires have a coating of an insulating material. The material, generally used is (a)Lead (b)Graphite (c)PVC (d)All can be used. Solution: (c).PVC (Poly Vinyl Chloride) coatings are generally used for insulating electrical wires....
Read More →Generally, non-metals are not conductors of electricity.
Question: Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity ? (a)Diamond (b)Graphite (c)Phosphorus (d)Iodine Solution: (b).Graphite is a good conductor of electricity....
Read More →Although metals form basic oxides,
Question: Although metals form basic oxides, which of the following metals form an amphoteric oxide ? (a)Na (b)Ca (c)Zn (d)Cu. Solution: (c).Zn forms amphoteric oxide ZnO which reacts with both the acids and the alkalies....
Read More →The electronic configurations of three elements X,
Question: The electronic configurations of three elements X, Y and Z are X 2, 8; Y 2, 8, 6 and Z 2, 8, 1. Which of the following is correct ? (a)X is a metal (b)Y is a metal (c)Z is a non-metal (d)Y is a non-metal and Z is a metal. Solution: (d).Y is sulphur (S) while Z is sodium (Na)...
Read More →Tick (✓) the correct answer
Question: Tick (✓) the correct answer $\frac{x+5}{2}+\frac{x-5}{3}=\frac{25}{6}$ gives (a) $x=3$ (b) $x=4$ (c) $x=5$ (d) $x=2$ Solution: (b) $x=4$ $\frac{x+5}{2}+\frac{x-5}{3}=\frac{25}{6}$ $\Rightarrow \frac{3(x+5)+2(x-5)}{6}=\frac{25}{6}$ (because L.C.M. of $2 \ 3$ is 6 ) $\Rightarrow \frac{3 x+15+2 x-10}{6}=\frac{25}{6}$ $\Rightarrow \frac{5 x+5}{6}=\frac{25}{6}$ $\Rightarrow 5 x+5=25$ (cancelling 6 from the denominator on both the sides) $\Rightarrow 5 x=25-5$ $\Rightarrow 5 x=20$ $\Rightarr...
Read More →Reaction between the elements X and Y results
Question: Reaction between the elements X and Y results in the compound Z. Whereas X loses electron, Y gains the same. Which of the following properties is not shown by Z ? (a)Has high melting point (b)Has low melting point (c)Conducts electricity in molten state (d)Occurs as solid Solution: (b).Z is an ionic compound. Therefore, it is not expected to have low melting point....
Read More →Which among the following alloys
Question: Which among the following alloys contain mercury as one of its constituents ? (a)Stainless steel (b)German silver (c)Solder (d)Zinc amalgam. Solution: (d).All amalgams contain mercury as one of their constituents....
Read More →Mark (✓) against the correct answer:
Question: Mark (✓) against the correct answer: 8x3 2x= ? (a) (4x 1)(2x 1)x (b) (2x2+ 1)(2x 1) (c) 2x(2x 1)(2x+ 1) (d) none of these Solution: (c) 2x(2x 1)(2x + 1) $8 x^{3}-2 x$ $=2 x\left(4 x^{2}-1\right)$ $=2 x\left((2 x)^{2}-1^{2}\right)$ $=2 x(2 x-1)(2 x+1)$...
Read More →Define a function as a set of ordered pairs.
Question: Define a function as a set of ordered pairs. Solution: Function as a set of ordered pairs: A function is a set of ordered pairs with the property that no two ordered pairs have the same first component and a different second component. The domain of a function is the set of all first components, x, in the ordered pairs and the range of a function is the set of all second components, y, in the ordered pairs. For. e.g. $\{(1, x),(2, y),(3, z)\}$ is a function, since there are no two pair...
Read More →Which of the following statements is
Question: Which of the following statements is not correct for magnesium metal ? (a)It burns in oxygen with dazzling flame (b)It reacts with cold water to form magnesium oxide and evolves hydrogen gas (c)It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas (d)It reacts with steam to form magnesium hydroxide and evolves hydrogen gas. Solution: (b).Magnesium (Mg) does not react with cold water since its position in the reactivity series of metals is not at the top....
Read More →Define a function as a set of ordered pairs.
Question: Define a function as a set of ordered pairs. Solution: Function as a set of ordered pairs: A function is a set of ordered pairs with the property that no two ordered pairs have the same first component and a different second component....
Read More →Alloys are homogeneous mixtures of a metal
Question: Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents ? (a)Brass (b)Gun metal (c)Amalgam (d)Steel. Solution: (d).Steel (stainless) contains very small percentage of carbon....
Read More →An element ‘X’ is soft and can be cut with a knife.
Question: An element X is soft and can be cut with a knife. This is very reactive to air and cannot be kept in open air. It reacts vigorously with water. Identify the element from the following (a)Mg (b)Na (c)S (d)Mg Solution: (b).Sodium (Na) gives all the characteristics of the element X....
Read More →Tick (✓) the correct answer
Question: Mark (✓) against the correct answer: 10p2+ 11p+ 3 = ? (a) (2p+ 3)(5p+ 1) (b) (5p+ 3)(2p+ 1) (c) (5p 3)(2p 1) (d) none of these Solution: (b) (5p+ 3)(2p + 1) $10 p^{2}+11 p+3$ $=10 p^{2}+5 p+6 p+3$ $=5 p(2 p+1)+3(2 p+1)$ $=(5 p+3)(2 p+1)$...
Read More →During electrolytic refining of copper,
Question: During electrolytic refining of copper, ir gets (a)deposited on cathode (b)deposited on anode (c)deposited on cathode as well as anode (d)remains in the solution. Solution: (a).Pure metal is always deposited on cathode....
Read More →Tick (✓) the correct answer
Question: Mark (✓) against the correct answer: 12x2+ 60x+ 75 = ? (a) (2x+ 5)(6x+ 5) (b) (3x+ 5)2 (c) 3(2x+ 5)2 (d) none of these Solution: (c) $3(2 x+5)^{2}$ $12 x^{2}+60 x+75$ $=3\left(4 x^{2}+20 x+25\right)$ $=3\left((2 x)^{2}+2 \times 2 x \times 5+5^{2}\right)$ $=3(2 x+5)^{2}$...
Read More →An electrolytic cell consists of :
Question: An electrolytic cell consists of : (i) positively charged cathode (ii) negatively charged anode (iii) positively charged anode (iv) negatively charged cathode (a)(i) and (ii) (b)(iii) and (iv) (c)(i) and (iii) (d)(ii) and (iv) Solution: (b)(iii) and (iv)...
Read More →An alloy is :
Question: An alloy is : (a)an element (b)a compound (c)a homogeneous mixture (d)a heterogeneous mixture Solution: (c).An alloy is a homogeneous mixture of two or more elements (metals or non-metals.)...
Read More →Tick (✓) the correct answer
Question: Mark (✓) against the correct answer: 7x2 19x 6 = ? (a) (x 3)(7x+ 2) (b) (x+ 3)(7x 2) (c) (x 3)(7x 2) (d) (7x 3)(x+ 2) Solution: (a) (x 3)(7x + 2) $7 x^{2}-19 x-6$ $=7 x^{2}-21 x+2 x-6$ $=7 x(x-3)+2(x-3)$ $=(x-3)(7 x+2)$...
Read More →5 mL each of concentrated HCl, HNO3 and a mixture of concentrated
Question: 5 mL each of concentrated HCl, HNO3and a mixture of concentrated HCl (15 mL) and concentrated HNO3(5 mL) were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C. The metal could be (a)Al (b)Au (c)Cu (d)Ag Solution: (b).Gold (Au) dissolves in aqua regia....
Read More →Which one of the following four metals
Question: Which one of the following four metals would be displaced from the solution of its salts by other three metals ? (a)Mg (b)Cu (c)Zn (d)Fe Solution: (b).Cu is the least reactive and would be displaced from its salts by other metals....
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