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2 years ago

7

Density is calculated by combining 2 units, therefore the unit we use to measure density is called a _____________________unit.

What is the unit?

1 answer:

nalin [4]2 years ago

8 0

Answer: Dependent Unit or System of Units

Explanation:

Density is calculated by dividing mass (Kg) by volume (L).

The unit of Density is Kg/L or one of their derivatives such as g/cm³.

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This exercise uses the radioactive decay model. After 3 days a sample of radon-222 has decayed to 58% of its original amount. (a

Vadim26 [7]

Answer: a) 3.85 days

b) 10.54 days

Explanation:-

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = ?

t = time taken for decomposition = 3 days

a = let initial amount of the reactant = 100 g

a - x = amount left after decay process = $\frac{58}{100}\times 100=58g$

First we have to calculate the rate constant, we use the formula :

Now put all the given values in above equation, we get

$k=\frac{2.303}{3}\log\frac{100}{58}$

$k=0.18days^{-1}$

a) Half-life of radon-222:

$t_{\frac{1}{2}}=\frac{0.693}{k}$

$t_{\frac{1}{2}}=\frac{0.693}{0.18}=3.85days$

Thus half-life of radon-222 is 3.85 days.

b) Time taken for the sample to decay to 15% of its original amount:

where,

k = rate constant = $0.18days^{-1}$

t = time taken for decomposition = ?

a = let initial amount of the reactant = 100 g

a - x = amount left after decay process = $\frac{15}{100}\times 100=15g$

$t=\frac{2.303}{0.18}\log\frac{100}{15}$

$t=10.54days$

Thus it will take 10.54 days for the sample to decay to 15% of its original amount.

3 0

3 years ago

In magazine car tests an important indicator of performance is the zero to 60 mph (0 to 96.6 km/h) acceleration time. A time bel

slavikrds [6]

Answer:

2.73414 seconds

467622.66798 J

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

g = Acceleration due to gravity = 9.81 m/s² = a

$v=60\times \dfrac{1609.34}{3600}=26.822\ m/s$

$mgh=\dfrac{1}{2}mv^2\\\Rightarrow h=\dfrac{v^2}{2g}\\\Rightarrow h=\dfrac{26.822^2}{2\times 9.81}\\\Rightarrow h=36.66766\ m$

$s=ut+\frac{1}{2}at^2\\\Rightarrow 36.66766=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{36.66766\times 2}{9.81}}\\\Rightarrow t=2.73414\ s$

or

$v=u+at\\\Rightarrow t=\dfrac{v-u}{a}\\\Rightarrow t=\dfrac{26.822-0}{9.81}\\\Rightarrow t=2.73414\ s$

The time taken is 2.73414 seconds

The potential energy is given by

$U=mgh\\\Rightarrow U=1300\times 9.81\times 36.66766\\\Rightarrow U=467622.66798\ J$

The change in potential energy is 467622.66798 J

5 0

3 years ago

Which statement correctly describes why a compound is a pure substance?

ad-work [718]

Explanation:

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two.

6 0

3 years ago

About ________ percent of wais scores fall between 70 and 130.

stiv31 [10]

It is about 95%. The Wechsler Adult Intelligence Scale-IV is an IQ test that is given by therapists and measures worldwide scholarly working. It incorporates both verbal and nonverbal parts. The normal score for all tests and subtests is 100; therefore, a score of more than 100 is better than expected and beneath 100 is underneath normal.

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3 years ago

13. in batesian mimicry, a palatable species gains protection by mimicking an unpalatable one. imagine that individuals of a pal

fiasKO [112]

Batesian mimicry is an adaptive feature associated with the coloration of a given species in a given environment.

<h3>What is Batesian mimicry?</h3>

Batesian mimicry can be defined as a type of adaptive feature associated with the coloration of a particular species and/or population.

On the first island, the color of the population won't change because of the absence of predators.

On the second island, the color of the population will change because of the presence of predators that can be alerted by the color.

On the third island, the color of the population won't change because of the presence of a species with a similar color.

In conclusion, Batesian mimicry is an adaptive feature associated with the coloration of a given species in a given environment.

Learn more about Batesian mimicry here:

brainly.com/question/14139071

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6 0

2 years ago