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2 years ago

When must scientist conduct controlled experiments ?

1 answer:

8 0

Usually when scientist wants to test whether one compound or one phenotype is related to another phenotype. Then they need to control this variable when conducting experiments.

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States of Matter Escape Room

iris [78.8K]

Answer:

Explanation:

matter has mass and undergoes a phase change

3 0

2 years ago

4. DBearded waste of Co-60 must be stored until it is no longer radioactive. Cobalt-60

Bingel [31]

464 g radioisotope was present when the sample was put in storage

<h3>Further explanation</h3>

Given

Sample waste of Co-60 = 14.5 g

26.5 years in storage

Required

Initial sample

Solution

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

t = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

Half-life of Co-60 = 5.3 years

Input the value :

$\tt 14.5=No.\dfrac{1}{2}^{26.5/5.3}\\\\14.5=No.\dfrac{1}{2}^5\\\\No=\boxed{\bold{464~g}}$

8 0

2 years ago

Which row probably contains the largest atoms on the periodic table?

svp [43]

The last row going across

7 0

3 years ago

When most liquids freeze, explain what happens to the motion and the space between the atoms.

KiRa [710]

Answer:

atoms relative motion slow down and begin to vibrate in place

8 0

2 years ago

Identify and explain exothermic and endothermic reactions in terms of energy transfer

Ulleksa [173]

Exothermic reaction is when the system releases energy to the surrounding, the energy (in the perspective of the system) will have a sign of negative, as the system is transferring energy towards the surrounding.

Endothermic reaction is when the system is absorbing energy from the surrounding, the energy (in the perspective of the system) will have a sign of positive, as energy is transferred to the system.

5 0

3 years ago