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>
The correct answer is that it is made of atoms that are covalently bonded together. Hope this helps.
<span>In water, naoh almost completely separates into na+ and oh- ions. thus, naoh is Stong base.
Strong bases and strong acids completely ionized in the water,So when NaOH is added into water, it is completely ionized and forms Na+ and OH- ions and it shows that it is a strong base.</span>
The type of bond between two elements can be predicted by measuring the electronegativity difference between the two atoms. Based on this difference the type of bonds are classified as,
E.N difference between 0.0 to 0.3 = Non Polar bond
E.N difference between 0.4 to 1.0 = Moderate Polar Covalent Bond
E.N difference between 1.1 to 2.0 = Very Polar Covalent Bond
E.N difference greater than 2.0 = Ionic Bond
So,
(E.N of N) 3.04 - (E.N of C) 2.55 = 0.49
As the difference is between 0.4-1.0, So, the bond between C and N is Moderate Polar Covalent Bond (or Polar Covalent Bond).
