The answer to this item depends entirely to the chemical reaction. If the compound, NH4Cl, is in the left hand side of the reaction, when it is added, the reaction will shift to the left. In the same manner, when the compound is in the right-hand side of the reaction, the reaction will shift to the right.
This happens because initially the reaction is in equilibrium and adding another compound to it will most likely lead to the shifting of the reaction.
Answer: The correct option is 3.
Explanation: We are given a compound which is made up of iron and oxygen only. The ratio of the two are given as:

This means that, number of iron ions are 2
Number of oxide ions are 3
From the above information, the formula becomes : 
The valency of iron = 3
Valency of oxide = 2
This compound is named as iron (III) oxide.
Hence, the correct option is 3
Saliva is composed of a variety of electrolytes, including sodium, potassium, calcium, magnesium, bicarbonate, and phosphates. Also found in saliva are immunoglobulins, proteins, enzymes, mucins, and nitrogenous products, such as urea and ammonia.
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