Answer:
They all have the same number of protons but different numbers of neutrons.
Explanation:
Elements will always have the same number of protons no matter the isotopes. Isotopes only change the number of neutrons. Silicon will always have 14 protons. So silicon-28 has 14 protons and 14 neutrons. Silicon-29 has 14 protons and 15 neutrons. Silicon-30 has 14 protons and 16 neutrons.
It was disproved by the discovery of the electrons
In the problem, we are tasked to solved for the amount of carbon (C) in the acetone having a molecular formula of C 3 H 6 O. We need to find first the molecular weight if Carbon (C), Hydrogen (H), Oxygen (O).
Molecular Weight:
C=12 g/mol
H=1 g/mol
O=16 g/mol
To calculate for the percent by mass of acetone, we assume 1 mol of acetone.
%C=

%C=62.07%
Therefore, the percent by mass of carbon in acetone is 62.07%
Answer: New pressure inside the flask would be 148.8 kPa.
Explanation: The combined gas law equation is given by:

As the flask is a closed flask, so the volume remains constant. Temperature is constant also.
So, the relation between pressure and number of moles becomes



- Final conditions: When additional 3 puffs of air is added

Putting the values, in above equation, we get

Answer;
The total pressure is 1.107 atm.
Explanation;
The total pressure is the sum of the pressures of the three gases in the flask
Pressure (total) = 0.215 atm + 0.066 atm + 0.826 atm = 1.107 atm
= 1.107 atm.