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lisabon 2012 [21]

3 years ago

15

Describe the way the moon moves in space?

1 answer:

Scilla [17]3 years ago

4 0

Gravitational Pull, is the answer. just like we orbit the sun, the moon orbits us. we act almost like a magnet, we follow the biggest guy as leader. if the sun dissapeared, we would die, but probably, we would start to revolve around jupiter as it is the biggest

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A block of ice has little thermal energy. If you place it in a warm room, it melts into warm liquid water, which has much more e

Naily [24]

<u>Answer:</u>

<em>The energy to turn the ice into water:</em>

The energy that is required to change the state of ice into a liquid is obtained in the form of heat energy from the ambient temperature of the warm room.
Once this heat energy is absorbed, the individual molecules of ice gain kinetic energy and start vibrating faster.
Yet, the temperature of the ice remains constant until the ice reaches its melting point because this energy is first utilised to break all the bonds of the lattice structure of the ice.
After all the bonds are broken and all of the ice has changed into water, if more heat is provided again, then the temperature of the water will increase.

8 0

3 years ago

Write the simple equation that describes the action of the enzyme catalase.

Nataly [62]

Here we have to write a simple equation which describes the action of the enzyme catalase.

The equation is: The concentration of the complex [ES] = $\frac{[E]0}{1+\frac{Km}{[S]} }$

Let us consider an enzyme catalyses reaction E + S ⇄ ES → E + P

Where E, S, ES and P are enzyme, substrate, complex and product respectively.

The concentration of the complex [ES] = $\frac{[E]0}{1+\frac{Km}{[S]} }$ , where $K_{m}$ is the Michaelis constant.

[E]₀ and [S] is the initial concentration of enzyme and concentration of substrate respectively.

5 0

3 years ago

What feature is forming ?

IRISSAK [1]

Answer:

Earthquake

Explanation:

Notice how it is starting to shift allowing the earthquake to form.

3 0

3 years ago

How many moles are in 153 grams of O2?

Tatiana [17]

Answer:

4.78 mol O2

Explanation:

Grams --> moles

Grams/molar mass = moles

153 g O2 / 32 g/mol O2 = 4.78125 (significant figures so round it up; the grams has 3 significant figures, so round it up) 4.78 mol O2

8 0

3 years ago

The radioactive isotope of lead, Pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.

Marina86 [1]

Answer:

Therefore it will take 7.66 hours for 80% of the lead decay.

Explanation:

The differential equation for decay is

$\frac{dA}{dt}= kA$

$\Rightarrow \frac{dA}{A}=kdt$

Integrating both sides

ln A= kt+c₁

$\Rightarrow A= e^{kt+c_1}$

$\Rightarrow A=Ce^{kt}$ [ $e^{c_1}=C$ ]

The initial condition is A(0)= A₀,

$\therefore A_0=Ce^{0.k}$

$\Rightarrow C=A_0$

$\therefore A=A_0e^{kt}$ .........(1)

Given that the $Pb_{209}$ has half life of 3.3 hours.

For half life $A=\frac12 A_0$ putting this in equation (1)

$\frac12A_0=A_0e^{k\times3.3}$

$\Rightarrow ln(\frac12)= 3.3k$ [taking ln both sides, $ln \ e^a=a$ ]

$\Rightarrow k=\frac{ln \frac12}{3.3}$

⇒k= - 0.21

Now A₀= 1 gram, 80%=0.8

and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram

Now putting the value of k,A and A₀in the equation (1)

$\therefore 0.2=1e^{(-0.21)\times t}$

$\Rightarrow e^{-0.21t}=0.2$

$\Rightarrow -0.21t= ln(0. 2)$

$\Rightarrow t= \frac{ln (0.2)}{-0.21}$

⇒ t≈7.66

Therefore it will take 7.66 hours for 80% of the lead decay.

3 0

3 years ago