Answer:
Oxygen
Explanation:
If two balloons are filled with hydrogen gas and helium gas respectively, then we want to identify what gas is in each balloon, we have to do so by exposing the both balloons to flame in an oxygen atmosphere.
Hydrogen combines with oxygen in the presence of a flame with quite a loud sound and the flame is sustained but when a flame is brought near helium gas in a balloon, the gas will only make a little sound when exposed to the flame and extinguish the flame.
The reason for the explosion of the gas in the hydrogen balloon is that combustion of hydrogen gas is exothermic. The heating up of surrounding air molecules leads to a sudden explosion.
However, the helium balloon makes a little sound when the balloon is ruptured releasing helium gas which extinguishes the flame.
Answer:
they causes climate change by trapping heat and also they contribute to respiratory diseases from smog and air pollution
Answer: Option (b) is the correct answer.
Explanation:
In a chemical reaction, the bonds between the reactant molecules tend to break leading to the formation of new bonds to produce products.
So, in order to break the bonds between the reactant molecules, energy is required to overcome the attraction between the atoms.
To form new bonds, energy gets released when two atoms come closer to each other. Hence, formation of bond releases energy.
As in the given reaction it is shown that 
< 0, that is, enthalpy change is negative. Hence, energy is released as it is an exothermic process.
Thus, we can conclude that the statement energy released as the bonds in the reactants is broken is greater than the energy absorbed as the bonds in the products are formed, is true about the bond energies in this reaction.
Answer:
It changed from unsaturated to saturated solution
Explanation:
Before adding the spatula tip full amount, the solution was unsaturated, but as soon as the spatula tip full amount was added and couldn't dissolve, it became unsaturated because it could not dissolve any more solute having already dissolved it maximum number of solute
<span>The water cycle is like a big circle and doesn’t really have a starting point. There are 4 main stages involved in water cycle i.e. evaporation, condensation, precipitation and runoff, so, I'd say you become water, you evaporate, then you turn into a cloud and rain, then runoff.</span>
