Option “B” is correct Calcium Carbonate is formed when CO2 is passed through lime water.
123. All isotopes of the same element have _________.
1. different atomic numbers and different atomic mass
2. different atomic numbers and the same atomic mass
3. the same atomic number but different atomic masses
4. the same atomic number and the atomic mass
Option “C” is correct All isotopes of the same element have the same atomic number but different atomic masses.
124. Nitric acid does not react with –
1. Gold
2. Copper
3. Zinc
4. Iron
Option “A” is correct Some precious metals such as pure gold and platinum do not react with nitric acid. Pure gold does react with aqua regia a mixture of concentrated nitric acid and hydrochloric acid.
125. In a car battery, electrolyte substance used is-
Option “B” is correct Electrolyte substance used in a car battery is Sulphuric acid (H_2 SO_4 ). It is a strong acid.
126. The average salinity of sea water is
1. 3%
2. 3.5%
3. 2.5%
4. 2%
Option “B” is correct On average, seawater in the world’s oceans has a salinity of approximately 3.5%, or 35 parts per thousand. This means that for every 1 litre (1000 mL) of seawater there are 35 grams of salts (mostly, but not entirely, sodium chloride) dissolved in it.
127. Because of impurities the boiling point of a liquid-
1. Increases
2. Decreases
3. Remains constant
4. They are not related
Option “A” is correct The boiling point of a liquid is the temperature at which its vapour pressure is equal to the pressure of the gas above it. Generally impurities increases the boiling point of liquid.
128. Change of water into the vapour is called-
1. Natural
2. Physical
3. Chemical
4. Biological
Option “B” is correct Change of water into the vapour is called a physical change.
129. Which one of the following is the hardest metal?
1. Gold
2. Iron
3. Platinum
4. Silver
Option “C” is correct Among non-metals, diamond is the hardest whereas, among the metals, platinum is the hardest.
130. These days yellow lamps are frequently used as street light. Which one of the following us used in these lamps:
1. Sodium
2. Neon
3. Hydrogen
4. Nitrogen
Option “A” is correct There are 2 types of street light bulbs are used by municipalities. They are sodium vapor and mercury vapor bulbs. The mercury vapor bulbs are usually a white ambient light and sodium on orange/yellow light.
