Nitrogen is classified as a gas and a nonmetal.
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Explanation:
Solar energy is the radiant energy emmitted from the Sun. It is the electromagnetic energy
Answer:
A) positive; added
Explanation:
Based on the reaction:
2NaHCO3(s) + 129kJ → Na2CO3(s) + H2(g) + CO2(g)
<em>2 moles of NaHCO3 requires 129kJ to produce 1 mole of Na2CO3, 1 mole of H2 and 1 mole of CO2.</em>
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That means, the energy must be added being, thus, an exothermic reaction. The exothermic reactions have ΔH >0.
Thus, right answer is:
A) positive; added
Answer:
In solid state all the atoms and molecules are held very closely together by strong attractive forces.
Explanation:
Solids have definite volume and shape.
In solids molecules are tightly pack and very close to each other.
Their melting and boiling point are every high.
The densities of solids are also very high as compared to the liquid and gas.
There are very strong inter molecular forces are present between solid molecules.
Consider the example of water. Which is present in three state solid, liquid and gas. In the form of ice its volume is less as compared to the liquid and gas, because molecules are tightly packed. If we melt the same ice we observe the volume is increase because molecules are now apart from each other. The distance between the molecules of water increased. If the same amount of water is evaporated the molecule of water will occupy all available space , and the distance between the water molecules get increased and inter molecular forces becomes negligible.