Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances.
Answer:
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴
Explanation:
Alpha beta and gamma radiations are the examples of ionizing radiations. When an atom is an excited state and having high energy, the atom is in unstable state. The excess of energy is released by the atom to get the stability. The released energy is in the form of radiations which may include alpha, beta, gamma, X-ray etc.
Alpha decay:
Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4 and atomic number less than 2 as compared to parent atom the starting atom.
Properties of alpha radiation:
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴
The nucleus of an atom is held together by the strong nuclear force to hold together protons and neutrons. The strong nuclear force is stronger than electricity and gravity. It's even the strongest out of the four fundamental forces.
The answer is A.
During any chemical change the total mass doesn’t changes. Whatever the total mass of starting materials was present the same mass of ending products is present in a chemical reaction.
Answer:
D) 0.50 mole of Ne
Explanation:
Given data:
Number of molecules of nitrogen = 3.0×10²³ molecules
Which sample contain same number of molecules as nitrogen= ?
Solution:
A) 0.25 mole of O₂
1 mole = 6.022×10²³ molecules
0.25 mol × 6.022×10²³ molecules / 1 mol
1.51×10²³ molecules
B) 2.0 moles of He.
1 mole = 6.022×10²³ molecules
2.0 mol × 6.022×10²³ molecules / 1 mol
12.044×10²³ molecules
C) 1.0 moles of H₂
1 mole = 6.022×10²³ molecules
D) 0.50 mole of Ne
1 mole = 6.022×10²³ molecules
0.50 mol × 6.022×10²³ molecules / 1 mol
3.0×10²³ molecules
