20. Answer is "it reflects sunlight".<span>
<span>The moon is </span>not a star<span> <span>as sun.
Hence, </span></span>moon can't produce light by itself<span>. The only reason that we can see the moon is </span>it reflects the sunlight<span>. According to the distance from the
sun to the moon, the light reflection can be varied.</span>
21. Answer is "Jupiter".
Asteroid
belt<span> <span>is
a </span></span>region which is located between
Mars and Jupiter and consists of asteroids and minor planets.<span> This asteroid belt has the </span>4%<span> <span>as the
mass </span>of our moon. Due to the </span>Jupiter's strong gravity<span>, it is </span>prevented a forming of new planet by this asteroid belt.
22.<span> Answer is "</span>they are equal".
The period of
revolution is
the time which is taken by a
mass to go completely one round around another mass. For moon, the period of revolution is 27 days.<span>
The period of
rotation</span> is
the time taken by a mass to complete
one round around its own axis. It is about 27 days for moon.
</span>23.<span> Answer is "</span>The moon is in Earth's shadow".
<span>Lunar eclipse happens when </span>Sun, Earth and moon are directly
aligned each other <span>and Earth is located in between the Sun and the
moon. </span>Then the moon is covered by the
Earth's shadow.
24.<span> Answer is "</span>In a solar eclipse, it is Earth that is caught in the umbra
of the moon. In a lunar eclipse, it is the moon that is caught in the umbra of
Earth".
In total lunar eclipse, Earth is located
between Sun and the moon and
they are directly aligned to each other. The moon is totally covered with the Earth's
shadow.
Total solar eclipse can be seen when the
moon is located between sun and Earth by completely covering the sun.
25. According
to the given choices, we can get "Apollo"<span> as the answer.
Apollo 8 is the first
manned mission to the moon. From
that there were several manned mission including <span>first
manned landing on the moon. The Apollo program was conducted by USA.</span> </span>
Covalent bond is the type of bond which involves the sharing of valence electrons between two atoms.
This bond usually arises from the equal attraction of the nuclei of the two atoms for the electrons shared.
Ionic bond, on the other hand, arises due to the transfer of electrons from the valence shell of one atom to the valence shell of the other.
An ionic compound that results from the reaction of an acid and a base is called a(n) salt. the cation in this compound comes from the base while the anion comes from the acid.
When an acid and a base are together, they react to counteract each other's effects and create a salt.
Water is created when the OH(-) anion of the base and the H(+) cation of the acid mix.
A salt is a substance that is created when an anion from an acid and a base combine.
Common table salt, NaCl, is created when sodium hydroxide and hydrochloric acid are combined.
The positive ion (cation) of a base and the negative ion (anion) of an acid make up a salt.
A neutralizing reaction occurs when an acid and a base interact. Additionally, sodium chloride, generally known as table salt, is referred to as salt.
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Ions are formed when atoms lose or gain electrons in order to fulfill the octet rule and have fuller valence electron shells.
