Those elements with similar properties are in the same column.
If a piece of charcoal is taken and set on fire it will evolve CO2 and heat. Charcoal is solid but carbon dioxide is gaseous. This is an example of change of state and evolve of heat during chemical reaction.
<u>Answer:</u> The average of the densities of the given measurements is 1.363 g/mL
<u>Explanation:</u>
The equation used to calculate density of a substance is given by:
We are given:
First measured value of density, 
= 1.019 g/mL
Second measured value of density, 
= 1.498 g/mL
Third measured value of density, 
= 1.572 g/mL
Putting values in above equation, we get:
Hence, the average of the densities of the given measurements is 1.363 g/mL
Answer:
The atomic number of<span>N<span>157</span></span>
The number of protons is 7
The number of electrons is 7
The number of neutrons is 8
Explanation:
The atomic number of Nitrogen is 7 because Nitrogen has 7 protons.
The seven protons attract 7 electrons in the ground state.
If the atom had fewer or more than 7 protons the atom would not be Nitrogen.
The mass of the atom is the sum of protons and neutron. so
p + n = mass ( protons (p) and neutrons(n) both have an atomic mass of one
7 + n = 15 subtract 7 from both sides
<span>7−7+n=15−7</span>
n = 8
