Which has the highest electronegativity value?
A
hydrogen
B
calcium
C
helium
D
fluorine d because fluorine has a higher group number
Answer : The enthalpy of the reaction is, -2552 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given enthalpy of reaction is,

The intermediate balanced chemical reactions are:
(1)

(2)

(3)

(4)

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :
(when we are reversing the reaction then the sign of the enthalpy change will be change.)
The expression for enthalpy of the reaction will be,



Therefore, the enthalpy of the reaction is, -2552 kJ/mole
Answer: Volatile
Explanation:
like ethanol(alcohol) it evaporates when you put it in the hand, really fast.
Some people think that it dries when it really evaporated at room temperature from liquid to gas
Explanation:
If the density of the object is more than that of water, it will sink. Otherwise it will float. The density of water is 1 g/mL.
Substance 1,
Mass, m = 450 g, Volume, V = 90 mL
Density = mass/volume
So,

It will sink.
Substance 2,
Mass, m = 35 g, Volume, V = 70 mL
Density = mass/volume
So,

It will float.
Substance 3,
Mass, m = 24 g, Volume, V = 12 mL
Density = mass/volume
So,

It will sink.
sodium hydroxide (NAOH) a.k.a causic soda commonly used in labs.
- MOLAR MASS of naoh is 39.997 g/mol.
- It is dry hard brittle, white stocks in large fused opaque white-stone like masses having a dense crystalline fracture in small pellets/flakes.
- it is very delinquent and one of the strongest base , acts as a saponifying agent which is used in industrial purposes.
- It is an important industrial chemical as it is used on its own and is also used as a raw material in the production of other chemicals. The basis for the production of sodium hydroxide is the electrolysis of brine.
To know more about sodium hydroxide visit :
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