science for 3 grade

Question: The number of electrons in the valence shell is equal to its ________. 1. atomic mass 2. group number 3. period number 4. atomic volume Answer: ..

Question: The fertilized egg is called ______________. 1. ovum 2. blastocyst 3. diploid cell 4. zygote Answer: ..

Question: Which of the following is not a bio-mass source? 1. Gobar gas 2. Coal 3. Wood 4. Nuclear energy Answer: ..

Carbon monoxide (CO): 12 parts by mass of carbon combines with 16 parts by mass of oxygen. Carbon dioxide (CO2): 12 parts by mass of carbon combines with 32 parts by mass of oxygen. Ratio of the masses of oxygen that combines with a fixed mass of carbon (12 parts) 16: 32 or 1: 2 For example, hydr..

Question: Define atomic mass of an element. Answer: The atomic mass of an element is the relative mass of its atom as compared to the mass of C - 12 atom taken as 12 unit..

Question: What is the effect of force in the following cases when - a) A fielder catches a cricket ball. b) Brakes are applied to a moving car. c) A player hits an in-coming ball with a hockey stick. d) A soft rubber ball is squeezed between your hands. e) A spring is stretched. f) A football ..

Question: Why is G called a universal constant? Answer: G is known as universal constant, because its value remains the same throughout the universe..

Question: Classify the following as element, compound or mixture. i) Zinc amalgam (ii) Sea water (iii) Iodine vapour (iv) Gold coin (v) Water. Answer: i) Mixture ii) Mixture iii) Element iv) Mixture v) Compoun..

Question: What are the sources of air pollutions? Answer: Some common sources of air pollution are: Carbon dioxide Carbon monoxide Oxides of sulphur Oxides of nitrogen Fluoride compounds Metals (e.g., lead, cadmium, nickel, arsenic, tin etc) Hydrocarbon (e.g., benzene) ..

Determine the period to which sodium (Na - 11) belon..