Answer:
is the activity, measured in of a 50 mg sample of 90-Sr.
Explanation:
Half life of the 90-Sr ,
Activity coefficient of the 90-Sr = 
Mass of 90-Sr = 50 mg = 0.050 g
Molecular mass of 90-Sr = 90 g/mol
Moles of 90-Sr =
Number of atom in 0.0005555 moles of 90-Sr:
1 year = 
Activity measured in atoms per seconds:
= Number of atoms ×
Water is made of 2 hydrogen and 1 oxygen atoms. The molecular weight for water should be 1+ 1+ 16= 18. Then the amount of water molecule in 11.4 gram of water should be: 11.4g/18= 0.63 moles.
Since 1 water means 2 hydrogen atoms, then the amount of hydrogen atom should be: 2/1 * 0.63= 1.26 moles of hydrogen
Answer:
The answer is heterogeneous mixture i think..
Answer:
1) B. increases
2) B. greater
3) C. Both A and B are correct
4) Activation energy
Explanation:
The rate of a chemical reaction is depend on temperature. If temperature increases, the chemical reaction also increases and vice versa. Fast reaction means which is completely in less time. So atoms in fast reaction have great activation energy and slow reaction have less activation energy. Collision occurs when the particles have energy to move and they collide in proper direction.
Answer:
element
A pure substance is matter that is uniform throughout and has consistent properties. All matter is made up of very small particles called atoms. Atoms are the building blocks of all matter. When a substance contains only one type of atom, it is called an element.
