Answer:
2.35 x 10²³atoms
Explanation:
Given parameters:
Number of moles of Be = 0.39moles
Unknown:
Number of atoms = ?
Solution:
To solve this problem:
1 mole of a substance contains 6.02 x 10²³ atoms
0.39 mole of Be will contain 0.39 x 6.02 x 10²³ = 2.35 x 10²³atoms
The mass of the air in the room is
50 kg.
V = lwh = 15.5 ft × 12.5 ft × 8 ft = 1550 ft³
1 ft = 12 in ×

= 30.48 cm
V = 1550 ft³ ×

= 4.39 × 10⁷ cm ³ = 4.39 × 10⁷mL = 4.39 × 10⁴ L
Mass = 4.39 × 10⁴ L ×

= 5.22 × 10⁴ g = 52.2 kg
Note: The answer can have only 1 significant figure, because that is all you gave for the height of the room.
To the correct number of significant figures, the mass of the air in the room is 50 kg.
The half-life of Plutonium−239, t1/2 is 2.41 × 10⁴<span> yrs
time taken to reach tolerable level = seven half-lives
= 7 x t1/2
= 7 x </span>2.41 × 10⁴ yrs
= 168700 yrs
= 1.687 x 10⁵ yrs
Hence, the period of time that <span>Plutonium-239 must be stored is </span>1.687 x 10⁵ years.
Answer:
The question you have provided is incomplete
Explanation:
Answer: 4.4 x 10^-7
Explanation:
The dissociation equation for this reaction is:
MgCO3 (s) → Mg+2 (aq) + CO3-2 (aq)
(Here 0.08 >>> x )

So the solubility MgCO₃ in a solution that containing 0.080 M Mg²⁺ is 4.4 x 10^-7