There are 2 significant figures in this number. A significant figure is any number that isn’t 0. Hope this helps.
<u>Answer:</u> The mass of gallium produced by the electrolysis is 0.0354 grams.
<u>Explanation:</u>
The equation for the deposition of Ga(s) from Ga(III) solution follows:

- To calculate the total charge, we use the equation:

where,
C = charge
I = current = 0.490 A
t = time required (in seconds) =
(Conversion factor: 1 min = 60 s)
Putting values in above equation, we get:

- To calculate the moles of electrons, we use the equation:

where,
C = charge = 147 C
F = Faradays constant = 96500

- Now, to calculate the moles of gallium, we use the equation:

where,
n = number of electrons transferred = 3
Putting values in above equation, we get:

- To calculate the mass of gallium, we use the equation:

Moles of Gallium = 
Molar mass of Gallium = 69.72 g/mol
Putting values in above equation, we get:

Hence, the mass of gallium produced by the electrolysis is 0.0354 grams.
Answer:
16.791 grams
Explanation:
The density formula is:

Rearrange the formula for m, the mass. Multiply both sides of the equation by v.


The mass of the gold nugget can be found by multiplying the density and volume. The density is 19.3 grams per cubic centimeter and the volume is 0.87 cubic centimeters.

Substitute the values into the formula.


Multiply. Note that the cubic centimeters, or cm³ will cancel each other out.


The mass of the gold nugget is 16.791 grams.
<em>Role of a catalysts in chemical reactions:</em>
<span><em>Catalyst is a substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.</em></span>
Answer:
isotopes
Explanation:
The atoms of a chemical element can exist in different types. These are called isotopes. They have the same number of protons (and electrons), but different numbers of neutrons. Different isotopes of the same element have different masses.