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
Answer:
m-9 = 3 is the required expression
1) 3x=(4x+50-30)/2
x=10
Explanation: (1/2)(big arc - small arc), plug in the numbers and solve
2) 15•x=33•10
x=22
Explanation: a•b=c•d, plug in the numbers and solve
3) (x+8)•8=(24+4)•4
x=6
Explanation: W•E=W•E, whole•external part= whole•external, plug in the numbers and solve
Answer:
A,C,D
Step-by-step explanation:
<span>4(6) + 7 (5 - 3 )
= 24 + 7(2)
= 24 + 14
= 38
answer
</span><span>D: 38</span>
