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1. Fill in the blanks : (a) Microorganisms can be seen with the help of a_____________________________. (b) Blue-green algae fix_____________________directly from air to enhance fertility of soil. (c) Alcohol is produced with the help of _______________________ .  (d) Cholera is caused by____________________ Ans. (a) microscope           (b) nitrogen           (c) yeast            (d) bacteria 2. Tick the correct answer : (a) Yeast is used in the production of (i) sugar (ii) alcohol. ✔️ (iii) Hydrochloric acid (iv) oxygen (b) The following is an antibiotic. (i) Sodium bicarbonate (ii) Streptomycin✔️ (iii) Alcohol (iv) Yeast  (c) Carrier of malaria-causing protozoan is  (i) female Anopheles mosquito ✔️ (ii) cockroach (iii) Housefly (iv) butterfly (d) The most common carrier of communicable diseases is  (i) ant (ii) Housefly✔️ (iii) Dragonfly (iv)Spider (e) The bread or idli dough rises because of because of (i) Heat (ii) grinding (iii) Growth of yeast cells✔️ (iv) kneading (f) The proce

 NCERT CLASS 8  CHAPTER :- 5 COAL AND PETROLEUM KEYWORDS SOLUTIONS KEYWORDS 📔 COAL :- A black or dark-brown combustible substance formed by carbonation of vegetable matter, used as a fuel. 📔 COAL GAS :- Coal gas is obtained during the processing of coal to get Coke . It is mainly used as a fuel in industries around coal processing plant. 📔 COAL TAR :- Coal Tar is a black, thick Viscous liquid and a mixture of almost hundreds of chemical compounds. 📔 COKE :- A synthetic fuel, obtained from destructive distillation of coal. 📔 FOSSIL FUELS :- Fuel formed from the dead remains of living organisms millions of year ago. 📔 NATURAL GAS :- Natural gas is one of the most useful, Clean and safe energy sources . When natural gas burns, it gives off a large amount of energy, and unlike other Fossil fuels, leaves no ash. 📔 PETROLEUM :- Petroleum oily , thick , flammable liquid , a mixture of various hydrocarbon formed from dead remains of living organisms. 📔 PETROLEUM REFINERY :- A pl

Ncert keywords Chapter = 4  MATERIAL : METAL AND NON-METELS KEYWORDS ⤵️ ▶️ATOM :-  The smallest unit of an element is called an Atom. ▶️CONDUCTER :- The meterial which allow heat and electricity to pass through them are called Conductor. ▶️ DISPLACEMENT REACTION :- A more reactive metal can replaces a less reactive metal,but a less reactive metal cannot save a more reactive metal is called Displacement Reaction. ▶️ DUCTILITY:- The property of metel by which it can be drawn into wires is called Ductility. ▶️ ELEMENT :- A pure substance made up of same atom is called Element.                     For example :- Gold iron...etc ▶️ MALLEABILITY :- The property of metals by which they can be beaten into thin sheets is called Malleability. ▶️ METALS :- The meterial which possess the characteristics of being hard,shiny, malleable, ductile, fusible.....etc are termed as metals.                           For example :- iron, silver, copper.....etc. ▶️Matalloids :- Element showing               p