Answer:
The atomic number
Explanation:
Transmutation refers to the conversion of one chemical element into another. A transmutation usually involves a change in the structure of atomic nuclei and this may be induced by a nuclear reaction.
Transmutation was first achieved in 1919 by Lord Rutherford when he successfully changed a nitrogen nucleus to an oxygen-18 isotope, producing a proton in the process.
Since transmutation often involves changing one atom into another, the atomic number or mass number of the original element always changes (to form a new element) in the process.
Answer: 2. cannot be an element.
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: methane 
Thus as it can be decomposed into its constituent elements, it is a compound.
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present.
Thus methane cannot be an element.
Answer:
A
Explanation:
Ball bounces because of the difference in the air pressure on the outside of the ball, and opposite the point of impact, and the pressure inside of the ball. This means that the inside of the ball now has less space to contain the air molecules contained inside the ball, increasing the pressure inside the ball.
Answer:
Option (2)
Explanation:
Since the amount of each sample is the same, we are looking for the metal with the greatest density, which is copper.
