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2 years ago

What is the half-life of a radioisotope if it decays to 25% of its original activity in 7 yr?

Chemistry

1 answer:

Pepsi [2]2 years ago

7 0

Answer:

3.5 yrs

Explanation:

If a sample has decayed to 25%, this means 2 half-lives have passed. We are given this is equal to 7 yrs, and it follows that one half life is 3.5 yrs.

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Find the specific heat of an unknown material with an initial temperature of 20°C, when 5000 Joules are applied to a 50 gram sam

xxTIMURxx [149]

Answer:

2J/g°C

Explanation:

Q = 5000J

Initial temperature (T1) = 20°C

Final temperature (T2) = 70°C

Specific heat capacity (c) = ?

Heat energy (Q) = mc∇T

Q = mc∇T

Q = mc(T2 - T1)

5000 = 50 × c × (70 - 20)

5000 = 50c × 50

5000 = 2500c

c = 5000 / 2500

c = 2J/g°C

The specific heat capacity of the substance is 2J/g°C

8 0

3 years ago

Truebor false is a substance is made of equal parts,the substance is knowns as complex substance

Alex

False i think im not sure

6 0

3 years ago

3. A PS6 plugged into a 120 V outlet uses 3 Amps. What is the Resistance rating of

blondinia [14]

Answer:

R = 40 ohms

Explanation:

Given that,

The voltage of outlet, V = 120 V

Current flowing through the device, I = 3 A

We need to find the Resistance rating of the power cord. Let the resistance is R. We know that,

Ohm's law, V = IR

Put all the values,

$R=\dfrac{V}{I}\\\\R=\dfrac{120}{3}\\\\R=40\ \Omega$

So, the resistance rating of the power cord is equal to 40 ohms.

8 0

3 years ago

14. Calculate the mass in grams of oxygen required to react completly with 0.75 moles of Aluminum.

cluponka [151]

3mols of O_2 react with 4mol of Al
3/4=0.75mol O_2 react with 1mol of Al

Moles of O_2:-

0.75(0.75)
0.5625mol

Mass of O_2:-

moles(Molar mass)
0.5625(32)
18g

Option B

8 0

2 years ago

What are destiny dependent factors

pochemuha

Answer:

Density dependent factors include disease, competition, and predation. Density dependant factors can have either a positive or a negative correlation to population size

Explanation:

hope this helps ;)

7 0

3 years ago

Read 2 more answers