I think the mass the mass was less than the original because a gas was released into the atmosphere. The mass in a chemical reaction is constant in a closed system according to conservation of mass law. However, if a chemical reaction is completed in an open system, mas changes may occur. In our case i think the change in mass was due to the release of hydrogen gas from the reaction to the atmosphere.
Answer:
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Answer:
False
Explanation:
There are two types of covalent bonding: polar covalent boding and nonpolar covalent bonding. During polar covalent bonding, the electrons are not shared evenly. This is due to the electronegativity differences between the two atoms. During nonpolar covalent bonding, the electrons are shared evenly.
Answer : The correct option is, (C)
Explanation :
A. 
This is synthesis reaction in which the two or more reactant react to give a single product.
B. 
This is combination reaction in which the two reactants combine to form a single product.
C. 
This is a neutralization reaction in which an acid react with a base to give a salt and water as a product.
D. 
This is a double displacement reaction in which the positive cation and negative anion of two reactants exchange their places to give two new products.
Hence, the reaction (C) is a neutralization reaction.
Answer: Physical change
Explanation: Condensation is the phase change of a gas to the liquid state. There is no formation of new products so it does not undergoes chemical change. Any phase change is considered a physical change.