Solubility products of Al(OH)3 and Zn(OH)2 are 8.5 × 10-23 and 1.8 × 10-4 respectively. If both Al3+ and Zn2+ ions are present in a solution, which one will be precipitated first on addition of NH4OH?
Al(OH)3
Zn(OH)2
Both (a) and (b)
None of these
In a reversible isothermal process, the change in internal energy is
zero
positive
negative
None of these
Based on the following thermochemical equations
H2O (g) + C(s) → CO (g) + H2 (g); H = 131 kJ
CO (g) + O2(g) → CO2 (g); H = -282 kJ
H2 (g) + O2 (g) → H2O (g); H =-242 kJ
C (s) + O2 (g) → CO2 (g); H = X kJ
the value of X will be
-393 kJ
-655 kJ
+393 kJ
+655 kJ
The sky looks blue due to
dispersion effect
reflection
transmission
scattering
D.
scattering
The blue colour of sky is due to the scattering of light by dust particles along with water suspended in air.
The first ionisation potential of Na, Mg, Al and Si are in the order
Na < Mg > Al < Si
Na > Mg > Al > Si
Na < Mg < Al > Si
Na > Mg > Al < Si
Elements of which group form anions most readily?
Oxygen group
Nitrogen group
Halogens
Alkali metals