The main factor that determines the stages a star will follow after the main sequence is the star's mass or size.
<h3>What is main sequence?</h3>
The main sequence of a star is a stage in the life cycle of that star. During the main sequence ( also called the zero age ), the star generates energy by nuclear fusion of Hydrogen atoms at the core of the star into Helium atoms. Eventually, the star runs out of hydrogen atoms, which concludes the main sequence. What happens afterward depends on the size of the star.
<h3>Low mass stars </h3>
For low-mass stars ( stars that are less than 0.1 times the mass of the sun), they slowly collapse into white dwarfs. These stars do not get hot enough to fuse helium atoms, instead hydrogen fusion continues until the whole star is filled with helium and slowly collapses into a white dwarf while it grows dimmer and colder.
<h3>Medium-sized stars</h3>
Medium-sized stars ( stars about 0.6 - 10 times the mass of our sun) become red giants. Stars similar in size to our sun are hot enough to fuse helium atoms, so towards the end of the main sequence it starts to fuse helium atoms, forming heavier elements like carbon and oxygen. The heavier elements move to the star's core due to gravity, while lighter elements like hydrogen form a shell around the core. This causes the sun to then grow in size, forming a red giant.
<h3>Large stars</h3>
Massive stars ( greater than 10 times the mass of the sun) and super-massive stars ( more than 40 times the mass of the sun ) end up exploding into a supernova , while the dense core collapses into a neutron star or a black hole.
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If the atoms that share electrons have an unequal attraction for electrons, the bond is called a Polar covalent bond.
<h3><u>Explanation:</u></h3>
A covalent chemical bond is formed in case of two different non-metals when one or more electron pairs are shared between bonding atoms. A difference in electronegativity of subsequent atoms of a covalent bond leads to formation of a small net charge around nucleus of each atom, pulling the shared electrons to one side of the bond, to the nucleus which has higher electronegativity.
HCl is an example of polar covalent bond and the HCl bond has Chlorine more electronegative. The bonding electrons are more close to Cl than H and hence Cl is partially negatively charged than H which has partial positive charge (HCl bond : 
). When electrons shared in a covalent bond have equal attraction, the bond is a Non-Polar covalent bond.
Answer:
An estimate for the time it will take for a spacecraft to travel from Earth to Mars is approximately 138.8 days
Explanation:
The distance between Earth and the Moon = 684,400 km
The distance between Earth and Mars = 220.58 × 10⁶ km
The distance between Earth and Pluto = 5.2241 × 10⁹ km
The ratio of the distance between Earth and Pluto and the distance between Earth and Mars = (5.2241 × 10⁹ km)/(220.58 × 10⁶ km) ≈ 23.683
It took 2006 to 2015 (9 years) to travel from Earth to Pluto, therefore, it can take approximately (9 years)/(23.683) ≈ 0.38 of a year which is ((9 years)/(23.683)) × 365.2422 ≈ 138.8 days for a spacecraft to travel from Earth to Mars
V = u + at where u is initial velocity (15 m/s), a is acceleration (2m/s^2) and t is time (15 seconds)
V = 15 + 2 X 15
V = 45 m/s
