98 elements are naturally forming elements.
Answer: 98
It's the emission of an electron when lights hit metal! Hope that helps! :)
Answer:
The enthalpy change of the reaction is -66.88 kJ/mol.
Explanation:
Mass of the solution = m = 100 g
Heat capacity of the solution = c = 4.18 J/g°C
Initial temperature of the solutions before mixing = 
Final temperature of the solution after mixing = 
Heat gained by the solution due to heat released by reaction between HCl and silver nitrate = Q


Heat released due to reaction = Q' =-Q = -334.4 J
Moles of silver nitrate = n
Molarity of silver nitrate solution = 0.100 M
Volume of the silver nitrate solution = 50.0 mL = 0.050 L ( 1 mL = 0.001 L)


Enthalpy change of the reaction = 

1 J = 0.001 kJ
The enthalpy change of the reaction is -66.88 kJ/mol.
Answer : The correct option is A.
Explanation :
The given chemical reaction is,

In the reaction, Reactants are present on the left side of the arrow and products are present on the right side of the arrow.
Reactants are those which takes part in and undergoes change during the reaction.
Products are those which are formed during the reaction.
In the given reaction, zinc react with hydrochloric acid to form zinc chloride and hydrogen gas.
Therefore, the reactants are zinc and hydrochloric acid.