Explanation:
12)
a) Sodium + oxygen = ?
When sodium reacts oxygen its forms sodium oxide as a product.
b) magnesium + fluorine = ?
When magnesium reacts with fluorine its forms magnesium fluoride as a product.
13)
a) 
Decomposition of mercury(II) oxide on heating gives out mercury and oxygen gas.
b)
The electrolytic decomposition of water gives out hydrogen gas amd oxygen gas.
Carbon was discovered in 3750 BC
Answer;
- It will sink because soap disrupts the inter-molecular forces of water
Explanation;
-A light twig is barely floating on the surface of water. if a drop of dish washing detergent is added near it then it will sink because soap disrupts the inter- molecular forces of water.
-The twig was initially floating due to the force of surface tension created by the inter-molecular forces between water molecules. When soap is added to the water, the twig will be driven to sink by the disruption of the water's surface tension. This is because soap is a surfacant that is amphipathic and thus disrupts the inter-molecular forces between water molecules that are responsible for surface tension.
Answer:
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- <em>The halogens posses </em><u><em>seven </em></u><em>valence electrons</em>
Explanation:
- <em>Valence electrons </em>are the electrons in the outermost orbitals of the atoms, which are the orbitals with the highest main energy level (principal quantum number).
- Halogens are the elements of the group 17 of the periodic table: F, Cl, Br, I, At.
- You can tell the number of valence electrons of the representative elements from the number of the group to which they belong. For the representative elements, the number of valence electrons equal the unit digit of the group number.
This table summarizes it:
Group number number of valence electrons
1 1
2 2
13 3
14 4
15 5
16 6
17 7
18 8
- So, in conclusion, <em>the halogens possess 7 valence electrons.</em>
Answer: 1
The first chemical reaction mentioned above represents a single replacement reaction; a reaction in which only one element is substituted by another element.
The second reaction shows a decomposition reaction; a reaction in which a compound is broken down into two more elements.
