Answer:
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Please give brainliest
The answer is Y
Step-by-step explanation:
You have to compare the numbers with conditions both in Rows and Columns.
Answer:
draw a right angle triangle
Step-by-step explanation:
Let one of the angles be A
cos A = sin (90-A)
90 - x - 20 = x
2x = 70
x = 35 degrees
Answer:
51 + 29+ 80
Step-by-step explanation:
she got this by adding 51 + 29