1. The most commonly used substance in fluorescent tubes are –
1. Sodium Oxide and Argon
2. Sodium Vapour and Neon
3. Mercury Vapour and Argon
4. Mercuric Oxide and Neon
Option “C” is correct Fluorescent lamp tube is filled with a gas containing low pressure mercury vapour and Argon. Sometimes gases like Xenon, Neon or Krypton can also be used. The pressure inside the lamp is around 0.3% of atmospheric pressure.
Option “A” is correct Limestone is a sedimentary rock composed largely of the minerals Calcite and Aragonite which are different crystals form of Calcium Carbonate (CaCO3). Limestone binds with silica and other impurities to remove them from the iron.
3. Monazite is an ore of-
1. Zirconium
2. Thorium
3. Titanium
4. Iron
Option “B” is correct Monazite is an important ore for Thorium, Lanthanum and Cerium. India, Madagascar and South Africa have large deposits of monazite sands.
Option “D” is correct Solid camphor directly changes into camphor vapour and this process is called sublimation. The sublimation is the process in which some substances upon heating directly changes into vapour from and when cooled again directly turns into solid form.
6. Which one of the following is liquid at ordinary temperature?
1. Lead
2. Nickel
3. Mercury
4. Tin
Option “C” is correct Mercury is the only metal which is liquid at ordinary temperature.
7. Which one of the following liquids is very good conductor of heat?
1. Mercury
2. Benzene
3. Ether
4. None of these
Option “A” is correct Mercury is a chemical element with the symbol (Hg). Mercury is used in thermometers due to its special properties. Mercury is good conductor of heat.
8. Match List-I with List-II and select the correct answer using the codes given below the lists:
1. a
2. b
3. c
4. d
Option “D” is correct Diamond is an allotrope of Carbon . Marble is a metamorphic rock composed mainly of crystalline calcium Carbonate or Calcium Magnesium Carbonate. The most common component of sand is Silicon dioxide in the form of quartz. Ruby is considered as one of the four precious stones together with Sapphire, Emerald and Diamond. In Chemistry, the ruby gemstone is a mixture of Aluminium, Oxygen and Chromium.
9. What is the reaction between an acid and a base called?
Option “C” is correct When an acid and a base are placed together, they react to neutralize the acid and base properties, producing a salt. This reaction is called Neutralisation.
10. Which among the following metal is used for galvanization?
1. Zinc
2. Copper
3. Iron
4. Silver
Option “A” is correct Galvanisation is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.
