131. What is the formula of potassium ion whose configuration is same as the noble gas state?
1.K+
2.K2+
3.K2-
4.K-
Option “A” is correct K+ is the formula of potassium ion whose configuration is same as the noble gas state.This means that potassium must have an electron configuration of 1s2,2s2,2p6,3s2,3p6
132. Which of the following is made up of Carbon only?
1. Kevlar
2. Lexan
3. Graphene
4. Spider silk
Option “C” is correct Graphene is an allotrope of Carbon in the form of a two dimensional atomic-scale hexagonal lattice in which one atom from each vertex.
133. The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing, is-
1. Argon
2. Xenon
3. Helium
4. Krypton
Option “C” is correct Hydreliox is a mixture of oxygen, helium, and hydrogen and is used for dives below 130 metres in commercial diving.
134. The rubbing surface of a matchbox has powdered glass and a little red ________________.
1. Antimony
2. Arsenic
3. Silicon
4. Phosphorus
Option “D” is correct The rubbing surface of a matchbox has powdered glass and a little red Phosphorus.
135. Crystallisation is an example of?
1. Physical Change
2. Chemical Change
3. Chemical Reaction
4. Galvanisation
Option “A” is correct Crystallisation is an example of physical change.
136. Vinegar and Baking Soda together produce ____________.
Option “D” is correct The resources which can be used continuously, year-after are called Renewable resources.
138. A balloon filled with helium rises in air because –
1. air exerts an upward force on the balloon
2. the balloon is weightless
3. helium is less dense than air
4. helium pushes down on the air below the balloon
Option “C” is correct Air contains 78% of nitrogen which is heavier than helium. Therefore, a balloon filled with helium rises in air because helium is less dense than air.
139. German silver, an alloy, does not contain the metal –
1. Nickel
2. Zinc
3. Copper
4. Silver
Option “D” is correct German silver is an alloy of having 60% copper, 20% nickel and 20% zinc. It is also known as Nickel Silver. Nickel silver is named for its silvery appearance, but it contains no silver.
140. Which of the following imparts a blue colour to glass?
Option “A” is correct The following metals imparts different colour to glasses- Cobalt oxide: deep blue colour; copper oxide: turquoise; chromium: dark green to black; cadmium sulphide: deep yellow etc.
