Which of the following noble gases is commonly found in the atmosphere?
Xenon
Neon
Helium
Argon
Correct answer is D
Argon, with the symbol Ar which is the third noble gas, in group 18 makes up about 1% of the Earth's atmosphere, making it the most common noble gas on Earth.
A suitable solvent for iodine and naphthalene is
carbon (IV) sulphide
ethanol
water
benzene
Correct answer is B
No explanation has been provided for this answer.
Hardness of water is mainly due to the presence of
calcium hydroxide or magnesium hydroxide
calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
sodium hydroxide or magnesium hydroxide
calcium chloride or sodium chloride salts
Correct answer is B
Salts of Calcium and Magnesium are responsible for hardness of water. Bicarbonates, Carbonates, Chlorides and Sulfates of Calcium and Magnesium causes temporary and permanent hardness.
What type of bond exits between an element X with atomic number 12 and Y with atomic number 17?
Electrovalent
Metallic
Covalent
Dative
Correct answer is A
No explanation has been provided for this answer.
The importance of sodium aluminate (III) in the treatment of water is to
cause coagulation
neutralize acidity
prevent goitre and tooth decay
kill germs
Correct answer is A
No explanation has been provided for this answer.