Fluorosis disease is caused due to the reaction of with excess of fluoride in the body.

• Ca

• Mg

• Fe

• K

Two oxides of nitrogen, NO and NO₂ react together at 253K and form a compound of nitrogen X. X reacts with water to yield another compound of nitrogen Y. The shape of the anion of Y molecule is :

• tetrahedral

• triangular planar

• square planar

• pyramidal

Chlorine atom, in its third excited state, reacts with fluorine to form a compound X. The formula and shape of X are :

• ClF₅,  pentagonal

• ClF₄, tetrahedral

• ClF₄, pentagonal bipyramidal

• ClF₇, pentagonal bipyramidal

In Fischer-Ringe's method of separation of nobles gas mixture from air ....... is used

• 90% CaC₂ + 10% CaCl₂

• coconut charcoal

• soda lime + potash solution

• 90% CaCO₃ + 10% urea

In the Dewar's method of separation of noble gases, the mixture of noble gases is kept in contact with coconut charcoal at 173 K. Which one of the following gaseous mixtures is not adsorbed on to the charcoal?

• Ar, Kr

• Xe, Ar

• He, Ne

• Xe, Kr

The chemical formula of 'tear gas' is

• COCl₂

• CO₂

• Cl₂

• CCl₃NO₂

Which of the following is not correct?

• Iodine oxidises sodium thiosulphate to sodium tetrathionate

• Sodium thiousulphate is soluble in water

• Ozone is used to identify the presence of unsaturation in alkenes

• Sodium thiosulphate reacts with iodine to form sodium sulphate

Which one of the following pairs of reactants does not form oxygen when they react with each other?

• F₂, NaOH solution (hot, conc.)

• F₂, H₂O

• Cl₂, NaOH solution (cold, dilute)

• CaOCl₂, H₂SO₄ (dilute, small amount)

909.

What is the correct order of occurrence (% by weight) in air of Ne, Ar and Kr ?

• Ne > Ar > Kr

• Ar > Ne > Kr

• Ar > Kr > Ne

• Ne > Kr > Ar

Hydrolysis of NCl₃ gives NH₃ and X. Which of the following is X?

• HClO₄

• HClO₃

• HOCl

• HClO₂