Option “A” is correct The Chemical Ethephon is often used on wheat, coffee, tobacco, cotton and rice in order to help the plant’s fruit to ripen more quickly.
92. Which of the following is not a Natural polymer?
1. Wool
2. Silk
3. Leather
4. Nylon
Option “D” is correct Wool, silk, leather are the natural polymers but nylon is not a natural polymer.
93. Which one of the following chemicals had been in use till now for making artificial clouds?
1. Potassium Nitrate
2. Heavy Water
3. Sulphur Iodide
4. Silver Iodide
Option “D” is correct Cloud seeding is the process of spreading either dry ice or more commonly silver Iodide into the upper part of clouds to try to stimulate the precipitation process and form rain.
94. ___________ Gases absorb long wave (infrared) radiation from the earth and emit it again towards the earth.
Option “C” is correct A greenhouse gases are combination of gases in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect.The main Greenhouse Gases are Carbon di oxide, Methane, Ozone, Water vapour etc.
95. Metals react with sodium hydroxide to produce ___________.
1. Oxygen gas
2. Sodium
3. Water
4. Hydrogen gas
Option “D” is correct Sodium hydroxide reacts with metal to release hydrogen gas. The metal takes the oxygen atom from sodium hydroxide, which in turn takes the oxygen atom from the water, and releases the two hydrogen atoms. The reaction thus produces hydrogen gas.
Option “C” is correct Calcium hydroxide base is present in lime water.
97. Chemical formula for Sulphurous acid is:
1.H2SO4
2.H2SO3
3.H3SO3
4.H3SO4
Option “B” is correct Sulfurous acid is the chemical compound with the formula H₂SO₃.
98. Brownish film formed on iron when left in open is called?
1. Dust
2. Shovel
3. Spade
4. Rust
Option “D” is correct When iron is exposed to water or air over a period of time, the iron reacts with oxygen in the presence of moisture to form a reddish-brown chemical compound, iron oxide. This is referred to as rust.
99. The substances which have very low ignition temperature and can easily catch fire with a flame are called _____________ substances.
Option “D” is correct The substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances. Examples of inflammable substances are petrol, alcohol, Liquified Petroleum Gas (LPG), etc.
100. Which of the following main elements is used in making matchbox?
1. Graphite
2. Phosphorous
3. Silicon
4. Sodium
Option “B” is correct The safety matchbox ignites due to the extreme reactivity of phosphorus with the potassium chlorate on the match head. Phosphorus is a highly reactive, non-toxic-chemical used for making the head of a matchstick.
