Chemistry

Permanent hardness of water can be removed by?

A. filtration B. adding slaked lime C. adding caustic soda D. boiling Correct Answer: Option C - adding caustic soda

5 years ago

A noble gas with a high power of fog penetration used in aerodrome beacons is?

A. krypton B. argon C. helium D. neon Correct Answer: Option D - neon

5 years ago

Elements in the same period in the periodic table have the same?

A. number of shells B. atomic number C. chemical properties D. physical properties Correct Answer: Option A - number of…

5 years ago

The maximum number of electrons in the L shell of an atom is?

A. 2 B. 8 C. 18 D. 32 Correct Answer: Option B = 8

5 years ago

The stability of the noble gases is due to the fact that they?

A. have no electron in their outermost shells B. have duplet or octet electron configurations C. belong to group zero…

5 years ago

How many unpaired electron(s) are there in the nitrogen sub-levels?

A. 3 B. 2 C. 1 D. none Correct Answer: Option A - 3

5 years ago

Moving from left to right across a period; the general rise in the first ionization energy can be attributed to the?

A. decrease in nuclear charge B. increase in nuclear charge C. decrease in screening effect D. increase in screening effect…

5 years ago

The droplets of water observed around a bottle of milk taken out of the refrigerator is due to the fact that the?

A. water vapour in the air around the bottle gains some energy from the bottle B. temperature of the milk…

5 years ago

Calculate the percentage by mass of nitrogen in calcium trioxonitrate (V) [Ca = 40, N = 14, O = 16]

A. 8.5% B. 13.1% C. 17.1% D. 27.6% Correct Answer: Option C = 17.1%

5 years ago

Which of the following is an example of a mixture?

A. Common salt B. Blood C. Sand D. Washing soda Correct Answer: Option B - Blood

5 years ago