Answer:
Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Amphoterism depends on the oxidation states of the oxide. Al2O3 is an example of an amphoteric oxide.
Answer:
<u>Covalent Bond:</u>
The bond formed by the sharing of electron pairs between atoms is called a covalent bond.
<u>For example:</u>
The bonds between H₂O are covalent bonds as they are formed as a result of sharing of electrons.
<u>Types:</u>
There are 5 types of covalent bond:
1) Single covalent bond
2) Double covalent bond
3) Triple covalent bond
4) Polar covalent bond
5) Non-polar covalent bond
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Hope this helped!
<h3>~AH1807</h3>
<u>Answer:</u> The formula of chromic acid is 
<u>Explanation:</u>
We are given an ionic compound named as chromic acid. This acid is formed by the combination of hydrogen ion and chromate ion.
An acid is defined as the substance which releases hydrogen ion when dissolved in water.
Hydrogen is the 1st element of periodic table having electronic configuration of
.
This element will loose 1 electron to form
ion.
Chromate ion is a polyatomic ion having chemical formula of 
By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.
So, the chemical formula for the given compound is 
Thus, the formula of chromic acid is 
Answer:
Oxygen - Proportions increased as plants released this gas into the atmosphere.
Water Vapor - Proportions decreased as this lighter gas was blown away by solar winds.
Hydrogen - Proportions increased as this gas was released through volcanic eruptions.
Ammonia - Proportions decreased as it reacted with other elements to form nitrogen.
Carbon Dioxide - Proportions decreases as plants used this gas during photosynthesis.