CHEMICAL FORMULAS The chemical formula of a compound is a symbolic representation of its chemical composition. Name of the Compound Formula Sodium hydroxide NaOH Phosphorus pentachloride PCl 5 Sulfur dioxide SO 2 Potassium bicarbonate KHCO 3 Methanol CH 3 OH Ammonium Carbonate (NH 4 ) 2 CO 3 Aluminium Oxide Al 2 O 3 Sodium oxide Na 2 O Aluminium Carbonate Al 2 (CO 3 ) 3 Acetic acid CH 3 COOH Aluminium Chloride AlCl 3 Sodium sulphate Na 2 SO 4 Benzene C 6 H 6 Sodium carbonate Na 2 CO 3 Acetone C 3 H 6 O Barium Chloride BaCl 2 Carbon tetrachloride CCl 4 Barium hydroxide
Science PYQs and IMP Qs Class 10th Science PYQs and Practice Questions for Board Exams 2023- 2024 ayushagarwal_maths MCQs Q.1 . Light of which of the following colour is scattered least ? (a) Violet (b) Red (c) Blue (d) Yellow Ans. (b) Red Q.2. In an electrolysis of water, if the mass of the gas collected at the anode is mₐ and the mass of the gas collected at the cathode is mc the value of (mc/mₐ) is : (a) 8 (b) 16 (c) 1/16 (d) 1/8 Ans. (d) 1/8 Q.3. The unit of electric energy is : (a) kilowatt (b) kilowatt-hour (c) watt (d) kilowatt per hour Ans. (b) kilowatt-hour Q.4. The average weight of an adult human brain is : (a) 1200 g (b) 1350g (c) 1450 g (d) 1500 g Ans. (b) 1350 g Q.5. In which life processes we take energy from food ? (a) Nutrition (b) Excretion (c) Circulation (d) All of these Ans. (a) Nutrition Q.6. Why do estrogen levels fall after menopause ? (a) Cells of
SQUARES AND SQUARE ROOTS Square number - The square of a number is the product of the number with the number itself. A given number is a perfect square if its prime factors can be expressed in pairs of equal factors. A perfect square number is never negative. For example - 8^2 = (8×8) = 64 Facts About Squares - 1. A number ending in 2, 3, 7 or 8 is never a perfect square. 2. A number ending in an odd number of zeros is never a perfect square. 3. The square of an even number is always even. 4. The square of an odd number is always odd. 5. The ending digits of a square number is 0, 1, 4, 5, 6, or 9 only. Note:- It is not necessary that all numbers ending with digits 0, 1, 4, 5, 6, or 9 are square numbers. Important Facts- 1. Numbers ending in an even number of zeros are not necessarily perfect squares. Eg- 3700, 290000, 47000000. Practice Questions :- 1. Find the square of 54 ? 2. What least number must be added to 5607 to mak
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