CBSE ADDA

1. Which of the following is the lightest metal ? (A) Mercury (B) Silver (C) Lithium (D) Lead 2. The most important ore of Aluminium is — (A) Bauxite (B) Calamine (C) Calcite (D) Galena 3. The element present in the largest amount in rocks and minerals is — (A) Carbon (B) Silicon (C) Hydrogen (D) Aluminium 4. An alloy used in making heating elements for electric heating devices is — (A) Solder (B) Alloysteel (C) Nichrome (D) German Silver 5. German Silver is an alloy of — (A) Copper, Silver & Nickel (B) Silver, Copper & Aluminium (C) Zinc, Copper & Nickel (D) Silver, Zinc & Nickel 6. Air is a/an — (A) Compound (B) Element (C) Mixture (D) Electrolyte 7. Which of the following is the best conductor of Electricity ? (A) Ordinary water (B) Sea water (C) Boiled water (D) Distilled water 8. Balloons are filled with — (A) Helium (B) Oxygen (C) Nitrogen (D) Argon 9. The charcoal used to decolourise raw sugar is — (A) Animal charcoal (B) Sugar charcoal (C) Cocoanut charcoal (D)

1.  Brass gets discoloured in air because of the presence of which of the following gases in air? A. Oxygen B. Hydrogen sulphide C. Carbon dioxide D. Nitrogen                Answer:  Option  B 2.  Which of the following is a non metal that remains liquid at room temperature? A. Phosphorous B. Bromine C. Chlorine D. Helium            Answer:  Option  B   3.  Chlorophyll is a naturally occurring chelate compound in which central metal is A. copper B. magnesium C. iron D. calcium  Answer:  Option  B 4.  Which of the following is used in pencils? A. Graphite B. Silicon C. Charcoal D. Phosphorous          Answer:  Option  A 5.  Which of the following metals forms an amalgam with other metals? A. Tin B. Mercury C. Lead D. Zinc         Answer:  Option  B 6.  Chemical formula for water is A. NaA1O 2 B. H 2 O C. Al 2 O 3 D. CaSiO 3 7.  The gas usually filled in the electric bulb is A. nitrogen B. hydrogen C. carbon dioxide D. oxygen         An

Which instrument is used to measure pressure? Saccharimeter Ammeter Manometer Lactometer What does Angstrom measure? Quantity of liquid Length of light waves Length of cables Speed of ships Light year is related to Energy Speed Distance Intensity Match the following columns Column 1 Column 2 A. Relative 1. Pyrometer humidity B. Anemometer 2. High temperature C. Navigation 3. Hygrometer D. Direction of wind 4. Chronometer 1 2 3 4 a. B D A C b. D B A C c. A D B C d. C A D B