A. physical change
Look at the way water freezes and changes to ice<span>. The matter is still going to be the same. its just the physical property that changed.
<u>PHYSICAL= TEMPORARY</u>
<u>CHEMICAL= PERMANENT</u></span>
In a closed system, the loss of momentum of one object is same as________ the gain in momentum of another object
according to law of conservation of momentum, total momentum before and after collision in a closed system in absence of any net external force, remains conserved . that is
total momentum before collision = total momentum after collision
P₁ + P₂ = P'₁ + P'₂
where P₁ and P₂ are momentum before collision for object 1 and object 2 respectively.
P'₁ - P₁ = - (P'₂ - P₂)
so clearly gain in momentum of one object is same as the loss of momentum of other object
W = mg
Weight on Earth = 50 x 9.8
= 490 N
Weight on Mars = 50 x 3.7
= 185 N
Answer: Equal number of protons and electrons. Example: an atom of oxygen atom has 8 electrons and 8 protons and is neutral.
Explanation:
An atom that has no charge is a neutral atom. It contains electrons equal to protons. For example: A neutral atom of oxygen has 8 protons and 8 electrons.
An atom which has charge is said be ionized. It is either positively charged or negatively charged. It is positively charge when the number of electrons is less than the number of protons. For example: 
contains 10 electrons and 11 protons.
And when the number of electrons is greater than the number of protons, the atom is negatively charged. For example, 
has 17 protons and 18 electrons. It readily accepts an electron to complete its octet.
