Answer:
element S is argon and element T is potassium.
4. B
5. D
Explanation:
in an element in periodic table number of elctrons and protons are same.
4. since element S has 18 protons so its atomic number must be 18 so the element is Argon which is the last element of period 4 so the next element will go to period 4 with one extra shell and since the atomic number of next element is 19 the element is Potassium. therefore T is Potassium.
5. number of nucleons in an atom is the number of protons and neutons combined together in an nucleus
1. gravity (gravitational pull from the sun brings all the planets into orbit)
2. the big bang.
3. hydrogen gas.
4. planets, moons, asteroids, and comets
5. it’s becomes a black dwarf star
Answer:
Catalysts help in increasing rates of reactions
Answer:

Explanation:
A physical change occurs when only the physical properties change. They are generally reversible and no new substances are formed.
However, in a chemical change, the chemical structures and properties change, plus new substances are formed.
Let's analyze each answer choice.
1. Change in state of matter
The state of matter is a physical property, so this is a physical change.
2. Precipitate was formed
A precipitate is a solid formed in a liquid solution. This is a new substance and a chemical change.
3. Unexpected change in odor.
A change in odor is a sign of chemical change.
4. Formation of bubbles
Bubbles signify the formation of gas or a new substance.
So, the best answer choice is <u>A. change in state of matter</u>