Chemistry - Study Mode

[#781] 'Atomic theory' of matter was given by
Correct Answer

(B) Dalton

Explanation

Solution: John Dalton (1766-1844) developed the first useful atomic theory of matter.

[#782] The most suitable unit for expressing nuclear radius is :
Correct Answer

(B) Fermi

Explanation

Solution: The most suitable unit for expressing nuclear radius is Fermi.

[#783] The total energy of revolving electron in an atom
Correct Answer

(C) Can never be positive

Explanation

Solution: The total energy of a revolving electron in any orbit is the sum of its kinetic and potential energies. Energy of an electron at infinite distance from the nucleus is zero. As an electron approaches the nucleus, the electron attraction increases and the energy of electron decreases and thus becomes negative. Thus, it can never be positive.

[#784] Which of the following is caused by the higher concentration of Nitrogen and Phosphorous ?
Correct Answer

(A) Eutrophication

Explanation

Solution: Higher concentration of Nitrogen and Phosphorus causes Eutrophication.

[#785] If the sewage is fully oxidized, the nitrogen is in the form of
Correct Answer

(D) Nitrates

Explanation

Solution: Oxidized forms of nitrogen include nitrite (NO 2 ) and nitrate (NO 3 ). Nitrogen mainly occurs in wastewater in this form. Because nitrite is easily oxidized to nitrate, nitrate is the compound predominantly found in groundwater and surface waters.