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Multiple Choice Questions

The most abundant element by mass in the body of a healthy human adult are :
Oxygen (61.4%) ; Carbon (22.9%), Hydrogen(10.0%) ; and Nitrogen (2.6%). The weight which a 75 kg person would gain if all 1H atoms are replaced by 2H atoms is

  • 15 kg

  • 37.5 Kg

  • 7.5 Kg

  • 7.5 Kg

1085 Views

A water sample has ppm level concentration of following anions

F-= 10; SO42- =100; NO3-= 50

the anion/anions that make/makes the water sample unsuitable for drinking is /are:

  • only NO3-

  • both 2 SO4- and NO3-

  • only F– 

  • only F– 

1043 Views

In the following reactions, ZnO is respectively acting as a/an :
(a) ZnO + Na2O → Na2ZnO2
(b) ZnO + CO2 → ZnCO3

  • base and acid

  • base and base

  • acid and acid

  • acid and acid

1312 Views

Both lithium and magnesium display several similar properties due to the diagonal relationship; however, the one which is incorrect is :

  • Both form basic carbonates

  • Both form soluble bicarbonates

  • Both form nitrides

  • Both form nitrides

1115 Views

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The radius of the second Bohr orbit for the hydrogen atom is :
(Plank's const. h = 6.6262 × 10–34 Js ; mass of electron = 9.1091 × 10–31 kg ; charge of electron
e = 1.60210 × 10–19 C ; permittivity of vacuum
∈0 = 8.854185 × 10–12 kg–1 m–3 A2)

  • 1.65Å

  • 4.76Å

  • 0.529Å

  • 0.529Å

702 Views

pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is

  • 7.2

  • 6.9

  • 7.0

  • 7.0

1598 Views

Δ U is equal to

  • Isochoric work

  • Isobaric work

  • Adiabatic work

  • Adiabatic work

1808 Views

The group having isoelectronic species is

  • O2– , F, Na+ , Mg2+

  • O– , F, Na, Mg+

  • O2–, F, Na ,Mg2+

  • O2–, F, Na ,Mg2+

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Which of the following molecules is least resonance stabilized?

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Given
C(grahite) + O2(g) → CO2(g)
ΔrH°  = - 393.5 kJ mol-1
H2(g) + 1/2O2(g) → H2O (l)
ΔrH°  = +890.3 kJ mol-1
Based on the above thermochemical equations, the value of ΔrH° at 298 K for the reaction
C(grahite) + 2H2(g) →CH4 will be

  •  +74.8 kJ mol–1 

  • +144.0 kJ mol–1

  • –74.8 kJ mol–1

  • –74.8 kJ mol–1

406 Views