Answer: 693 years
Step-by-step explanation:
Expression for rate law for first order kinetics is given by:

k = rate constant
t = time taken for decomposition = 1
= Initial amount of the reactant
= amount of the reactant left =



for half life : 

Putting in the values , we get


Thus half life of this isotope, to the nearest year is 693.
Answer:
i think its the same as one of the angles: 42º
correct me if im wrong
Answer:
The correct option is parallelogram ABCD is a rhombus, because the diagonal bisects two angles
Step-by-step explanation:
In triangle ABD:
∠B = ∠D
Thus AB=AC by the property of opposite sides of equal angles are equal
In triangle CBD
∠B = ∠D
Thus CB=CD by the property of opposite sides of equal angles are equal
Thus all four sides of quadrilateral ABCD are equal
And diagonal BD bisects the angles
So, it is a rhombus
Therefore the correct option is parallelogram ABCD is a rhombus, because the diagonal bisects two angles....
12 ÷ 3= 4. Hope this helps. ;)