Answer: A convex lens is used to converge ligtht.
Explanation:
A concave lens is a lens that is thicker on the ends than in the middle. As consequence of this, a concave lens diverges (separate) the rays of light. A concave lens is also called diverging lens.
A convex lens is is thicker in the middle than on the ends. As consequence of this, a convex lense converge the parallel rays that pass through it. A convex lens is also called converging lens.
Moving down in a group, the electronegativity decreases due to an increase in the distance between the nucleus and the valence electron shell, thereby decreasing the attraction, making the atom have less of an attraction for electrons or protons.
Answer: Option (b) is the correct answer.
Explanation:
It is known that metals are the species which readily lose an electron and tend to attain a positive charge.
For example, atomic number of sodium is 11 and its is an alkali metal. It electronic distribution is 2, 8, 1.
And, in order to attain stability it readily loses an electron and thus it become 
ion.
Also, it is known that species which tend to transfer or donate their valence electrons to other atoms tend to form ionic bond and the compound formed is known as ionic compound.
Therefore, we can conclude that the statement metal atoms held together by ionic bonds best describes a metal solid.
Hydrophobic molecules tend to be nonpolar molecules that group together to form micelles rather than be exposed to water. Hydrophobic molecules typically dissolve in nonpolar solvents (e.g., organic solvents).
