24No[2]
Q1 Mercury is liquid at 0°C due to _________ and _________
Q2An element in 3d transition series shows 2 oxidn states x an dy which differ by 2 units.Find conditions between x and y for compound to be ionic and covalent
Q3WHich acids attack copper and siver
a)dil HNO3
b)dil HCl
c)conc. H2SO4
d)aqua regia
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14 Answers
3q3)a,b i guess c,d wont come bcos copper forms a passive layer
q1)mercury has weak cohesive force dats y it exists as a liquid,but donno other reasons.
11Ans 1) Mercury is liquid at o ° C. The reason for this is that the very high ionisation energy makes it difficult for the electrons to participate in metallic bonding. Thus exposed mercury surfaces should be covered (for example with toulene), to prevent vapourization , and hence posioning. The gas is unusual bcoz it is monoatomic like the noble gases.
Not sure if this is the correct answer. Please correct me if I am wrong
1Ans 3 d.because aqua regia being a very strong acid(furnishing nascent Chlorine)is the only acid that reacts with noble metals like silver.
Conc H2SO4 forms oxide coating with them which hinders reaction.
1Also,Ag wont react with dil acids to displace Hydrogen from them,being lower than Hydrogen in metal activity series.
24Q1 options are...more htan one correct
a)very high ionization energy
b)weak metalic bonding
c)high heat of hydration
d)high heat of sublimation
1for Q3) dil. HCl ,aquaregia ,conc.H2SO4are attack as they form resp. precipitates..