It describes how, when particles/mc/elements react, despite forming different substances the mass is neither created nor destroyed but only converted.
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
Answer:
(a)
(b) 
Explanation:
The reaction that is carried out by the enzyme catalase produces
The reaction that is carried out by the enzyme catalase produces 
Answer:
Many emerging diseases arise when infectious agents in animals are passed to humans (referred to as zoonoses). As the human population expands in number and into new geographical regions, the possibility that humans will come into close contact with animal species that are potential hosts of an infectious agent increases.
Explanation:
Answer:
4.5g/mL
Explanation:
Given parameters:
Mass of ball = 36g
Volume of the ball = 8mL
Unknown:
Density of the ball = ?
Solution:
Density is the mass per unit volume of a substance.
Density =
So;
Density =
= 4.5g/mL