Answer is: nickel (Ni) is the most active metal.
Chemical reaction 1: Pb(NO₃)₂(aq) + Ni(s) → Ni(NO₃)₂(aq) + Pb(s).
Chemical reaction 2: Pb(NO₃)₂(aq) + Ag(s) → no reaction.
Chemical reaction 3: Cu(NO₃)₂(aq)) + Ni(s) → Ni(NO₃)₂(aq) + Cu(s).
From chemical reactions 1 and 3, we can conclude that nickel is more reactive than lead (Pb) and copper (Cu), because lead is more reactive than silver (Ag), chemical reaction 2, nickel is also more reactive than silver.
In chemical reaction 2, no reaction occurs because silver is less reactive than lead. Lead is higher in activity series of metals and can not be reduced.
Nickel is higher in activity series of metals than lead, copper and silver.
The activity series is a series of metals from highest to lowest reactivity. Metal higher in the reactivity series will displace another.
Answer : The temperature of the chloroform will be, 
Explanation :
First we have to calculate the mass of chloroform.
conversion used : 
Now we have to calculate the temperature of the chloroform.
Formula used :
where,
q = amount of heat or energy = 1.46 kJ = 1460 J (1 kJ = 1000 J)
= specific heat capacity = 
m = mass of substance = 110.958 g
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get:
Now we have to convert the temperature from Kelvin to Fahrenheit.
The conversion used for the temperature from Kelvin to Fahrenheit is:
As we know that, 
or, 
...........(1)
Now put the value of temperature of Kelvin in (1), we get:
Therefore, the temperature of the chloroform will be,
Answer:
D. Acidic salt
Explanation:
Acidic salts:
Salts formed by incomplete neutralisation of poly-basic acids are called acidic salts. Such salts still contain one or more replaceable hydrogen atoms. These salts when neutralised by bases form normal salts.
