Answer:
C) It provides a lower activation energy for the reaction is the correct answer.
Explanation:
- A catalyst increases the rate of the chemical reaction by lowering the activation energy for a reaction.
- Catalyst is used to increase the reaction rate, it remains unchanged in the chemical reaction and it does not change the equilibrium constant.
- Activation energy is a minimum amount of energy required to initiate the reaction.
Answer:
1
Explanation:
outershell atoms of an element are also known as valency of that element
so the valency and number of elctron in the outershell of a sodium atom is +1.
hope this will help
mark me as brilliant
Answer:
=> The colour of this stone is usually a pale greenish blue, owing to the presence of iron impurities. Stones that are treated with heat look more blue than green. On the Mohs scale of hardness, aquamarine ranges between 7.5 and 8 making it a relatively hard gemstone.
=> The best way to identify a real aquamarine stone is by looking at its colour. In its natural form, they have a pale blue colour, which is similar to seawater. They may have a slight green or yellow tint as well. Naturally occurring gems have excellent clarity and transparency.
=> The hardness of the stone is another feature you can use to identify the stone. Aquamarine stones are hard and they don’t get scratches easily. However, they can easily scratch glass and other such surfaces. So, if you find visible scratches on the stone, rethink your decision to buy it.
=> Most faceted aquamarine stones are clean to the eye and clear of any inclusions. However, translucent and opaque aquamarine is also available. These are usually fashioned into cabochons or beads. In some cases, inclusions may appear as parallel tubes. Such stones can be crafted to show a cat’s eye. Stones with cat’s eye and star effect are rare and highly priced.
<span>Na2CO3 (aq) + CaCl2H4O2 (aq) = CaCO3 (s) + 2 NaCl (aq) + 2 H2O (l)</span>