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horrorfan [7]
3 years ago
12

An unknown radioactive substance has a half-life of 3.20 hours . If 16.5 g of the substance is currently present, what mass A0 w

as present 8.00 hours ago
Chemistry
1 answer:
guajiro [1.7K]3 years ago
6 0

Answer:

the amount present 8 hours ago is Ao = 93.338 g

Explanation:

the radioactive decay is given by

A = Ao * 2^(- t/T)

where T = half-life of the substance , t= time , A= amount of substance at time t , Ao= amount of substance at time 0

therefore at t=8 hours , A=16.5 gr

Ao = A*2^(t/T) = 16.5 g * 2^(8 hours/3.20 hours) = 93.338 g

Ao = 93.338 g

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A solid rubber ball with a mass of 5.9 grams sank in water. A hollow rubber ball with the same mass floats in water. Explain why
Stells [14]

Answer:

The hollow ball is more buoyant than the solid ball.

Explanation:

The hollow ball will float while the solid ball sinks because the volume of water displaced by the hollow ball is more than that displaced by the solid ball.

An object floats when it displaces a volume of water equal to its weight.  A solid ball is more compact, and hence, does not displace a lot of water when dropped into a bowl full of water. On the other hand, the hollow ball will have a larger curved surface area, since it has no fill. This will make it displace a larger volume of water and hence make it float.

4 0
3 years ago
What is the cause of rising surface temperatures of the Pacific Ocean, drought in the Western United States, flooding on the pac
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Pretty sure it's D. El Nino but not positive.
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3 years ago
Partner Namets) For each of the following reactions carried out: Write the balanced chemical equation, the full ionic equation,
torisob [31]

Answer : The full balanced ionic equation will be,

2KI(aq)+Pb(NO_3)_2(aq)\rightarrow 2KNO_3(aq)+PbI_2(s)

Reactants are lead nitrate and potassium iodide.

Products are lead iodide and potassium nitrate.

The spectator ions are, K^+,NO_3^-

Explanation :

Complete ionic equation : In complete ionic equation, all the substance that are strong electrolyte and present in an aqueous are represented in the form of ions.

Net ionic equation : In the net ionic equations, we are not include the spectator ions in the equations.

Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.

When potassium iodide react with lead nitrate then it gives potassium nitrate and lead iodide as a product.

The full balanced ionic equation will be,

2KI(aq)+Pb(NO_3)_2(aq)\rightarrow 2KNO_3(aq)+PbI_2(s)

The ionic equation in separated aqueous solution will be,

2K^+(aq)+2I^{-}(aq)+Pb^{2+}(aq)+2NO_3^{-}(aq)\rightarrow PbI_2(s)+2K^+(aq)+2NO_3^{-}(aq)

In this equation, K^+\text{ and }NO_3^- are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,

Pb^{2+}(aq)+2I^{-}(aq)\rightarrow PbI_2(s)

4 0
3 years ago
We have two surfaces A and B where same amount of Force is acting. Area of Surface A is greater than Area of Surface B. which of
Phoenix [80]

Answer:

Pressure on Surface A > Pressure on Surface B

Explanation:

Pressu

re on Surface B > Pressure on Surface A

7 0
3 years ago
n acid with a pKa of 8.0 is present in a solution with a pH of 6.0. What is the ratio of the protonated to the deprotonated form
Nady [450]

Answer : The ratio of the protonated to the deprotonated form of the acid is, 100

Explanation : Given,

pK_a=8.0

pH = 6.0

To calculate the ratio of the protonated to the deprotonated form of the acid we are using Henderson Hesselbach equation :

pH=pK_a+\log \frac{[Salt]}{[Acid]}

pH=pK_a+\log \frac{[Deprotonated]}{[Protonated]}

Now put all the given values in this expression, we get:

6.0=8.0+\log \frac{[Deprotonated]}{[Protonated]}

\frac{[Deprotonated]}{[Protonated]}=0.01  

As per question, the ratio of the protonated to the deprotonated form of the acid will be:

\frac{[Protonated]}{[Deprotonated]}=100  

Therefore, the ratio of the protonated to the deprotonated form of the acid is, 100

5 0
2 years ago
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