Sodium chloride and prussic acid are formed
NaCN+HCl→NaCl+HCN
Answer: The correct option is 2.
Explanation: Heat flow is defined as the transfer of energy from hotter object to cooler object when two objects are kept together at different temperatures. As the energy remains conserved, so the heat flow will take place until the equilibrium is attained.
In the above asked question, Object A is at 40° C and Object B is at 80° C.
Object B is at higher temperature, so the heat flow will take place from Object B to Object A.
Hence, the correct option is 2.
A match-head is flammable, but you have to get it up to its ignition temperature first.
A diamond is flammable, but its ignition temperature is astronomical and
totally out of sight.
It would be an physical change ; if you melt butter the butter goes from a solid to a liquid so therefore the physical state is changed.