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If the opposite angular points of a square be (3,4) and (1,-1), find the coordinates of the remaining angular points . asked by ANKITA DHAL Solution: Let the coordinate of B and D be (x, y) and (x1, y1) respectively. Let AC and BD intersect at point O. Click below to download full soluttion
Solution:
C P of 1 toffee=10/11 SP of 1 toffee=10/9 Cost price of two toffees of different kinds = 10/11+ 10/9 =200/99 Therefore, combined cost price of one toffee =1/2 x 200/99 =100/99 It is given that, selling price of 1 toffee = Rs 1 As, C. P > S.P, therefore the seller get loss = (100/99) -1 =1/99 % Loss= [(1/99)/(100/99)]x 100%=1% Q. 5 g of calcium combine with 2 g of oxygen to form a compound. Find the molecular formula of the compound. (Atomic mass of Ca = 40 u; O = 16 u)
Ans. Number of moles in 5g of calcium = mass / molar mass = (5 / 40) = 0.125 Number of moles in 2g of oxygen = mass / molar mass = (2 / 16) = 0.125 Now we will calculate the simplest ratio of the element by dividing the number of moles of each element by the smallest value. Since number of moles of each element is 0.125, therefore calcium and oxygen are present in a ratio of 1 : 1. Thus the empirical formula of the compound is CaO. For calculating the molecular formula, we need the molecular mass of the compound. However, because a compound with the formula CaO is known, Therefore, the molecular formula of the compound is CaO. Q. (i) Name the body which approves the nomenclature of elements and compounds. (ii) The symbol of sodium is written as Na and not as S. Give reason. (iii) Name one element which form diatomic and one which form tetra atomic molecules. Ans. (i) IUPAC (International Union of Pure and Applied Chemistry) (ii) Latin name of sodium is Natrium. The first two letters (Na) of this name represents the symbol of sodium. (iii) Oxygen forms diatomic molecules and phosphorus forms tetra atomic molecules. Q. Calcium and Oxygen are combined in the rates of 5:4 by mass to form calcium oxide. What mass of Oxygen gas would be required to react with 2.5 g of calcium ? Ans: Calcium and oxygen combine in the rates of 5:4 by mass to form calcium oxide let x gram of oxygen is required to react with 2.5 g of calcium to form calcium oxide Therefore 5/4 = 2.5 / x then x = 2 Therefore 2 grams of oxygen is required to react with 2.5 grams of calcium to form calcium oxide . |