Answer:
B) a substance's color and odor changed Explanation: A signal that a chemical change has occurred is when its odor (its smell) or its appearance has changed.
Given question is incomplete. The complete question is as follows.
Balance the following equation:

Answer: The balanced chemical equation is as follows.

Explanation:
When a chemical equation contains same number of atoms on both reactant and product side then this equation is known as balanced equation.
For example, 
Number of atoms on reactant side:
H = 5
P = 1
O = 6
Ca = 1
Number of atoms on product side:
H = 6
P = 2
O = 9
Ca = 1
In order to balance this equation, we will multiply
by 2 on reactant side and we will multiply
by 2 on product side. Hence, the balanced chemical equation is as follows.

Answer:
6.564×10¹⁶ fg.
Explanation:
The following data were obtained from the question:
Mass of beaker = 76.9 g
Mass of beaker + salt = 142.54 g
Mass of salt in fg =?
Next, we shall determine the mass of the salt in grams (g). This can be obtained as follow:
Mass of beaker = 76.9 g
Mass of beaker + salt = 142.54 g
Mass of salt =?
Mass of salt = (Mass of beaker + salt) – (Mass of beaker)
Mass of salt = 142.54 – 76.9
Mass of salt = 65.64 g
Finally, we shall convert 65.64 g to femtograms (fg) as illustrated below:
Recall:
1 g = 1×10¹⁵ fg
Therefore,
65.64 g = 65.64 g × 1×10¹⁵ fg / 1g
65.64 g = 6.564×10¹⁶ fg
Therefore, the mass of the salt is 6.564×10¹⁶ fg.
Hydrogen exhibit similar properties with lithium because both are in the same group 1 as they both have a valence electron of 1
- Hydrogen also exhibit some similar properties with fluorine simply because they are both non metals
<h3>What is an element?</h3>
An element is a substance which cannot be split into simpler forms by an ordinary chemical process. This simply goes to say that elements are substances which cannot be decomposed into simpler substances by ordinary chemical reactions.
An atom is the smallest unit or part of an element which can take part in a chemical reaction.
On a general note, elements are classified as thus:
- Metals, non-metal, and metalloid.
- The extreme left side elements in the periodic table are metals, for example, aluminum, sodium, calcium, caesium, etc.
- However, elements on the right side are generally referred to as non-metals, carbon, chlorine, oxygen,
So therefore, hydrogen exhibit similar properties with lithium because both are in the same group 1 as they both have a valence electron of 1
- Hydrogen also exhibit some similar properties with fluorine simply because they are both non metals
Learn more about atoms and elements:
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