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2 years ago

When using goggles or face mask underwater, everything appears enlarged. Why?

1 answer:

3 0

What goggles and face masks are made of is a plastic or glass like version of a magnifying glass and it helps you see better like glasses

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The amount of stored chemical energy is what determines the temperature of a substance

Setler79 [48]

Answer:

False

Explanation:

Temperature is the degree of hotness or coldness of a body. Temperature is as a result of how much heat a body has. Heat is a form of energy called thermal energy. Heat can be transferred from one body to another as a result of differences in temperature between two bodies.

Chemical energy does not determine the temperature of a body. It is the amount of heat it contains.

3 0

3 years ago

Read 2 more answers

A student increases the temperature of a 417cm³ balloon from 278k to 231k. Assuming constant pressure, what should the new volum

viva [34]

Charles law states that volume of gas is directly proportional to temperature at constant pressure
V/T = k
where V - volume , T - temperature and k - constant
$\frac{V1}{T1} = \frac{V2}{T2}$
where parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation

in the question it states that the temperature has been increased from 278 K to 231 K but it should actually be temperature is decreased from 278 K to 308 K
substituting the values in the equation
$\frac{417cm^{3} }{278K} = \frac{V}{308 K}$
V = 462 cm³
the answer should be D. 462 cm³

3 0

2 years ago

What needs more gas a heavealy loaded truck or an empty truck

Vitek1552 [10]

A heavily loaded truck takes more gas because it takes more power to move a heavy load.

4 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

Adding O2 to the reaction 6CO2 + 6H2O <---> C6H12O6 + 6O2, WHICH WAY WILL THE REACTION SHIFT?

Alex73 [517]

Increase in Oxygen shift the equilibrium towards reactant side.

<u>Explanation:</u>

6CO₂ + 6H₂O ⇄ C₆H₁₂O₆ + 6O₂

This is the reaction occurs in the photosynthesis of plants by means of sunlight. In this case, if the concentration of Oxygen increases or adding more oxygen to the product side will shift the equilibrium towards the reactant side according to the Le Chatlier's principle, which adjusts the equilibrium by itself for any changes that is increase or decrease in pressure, temperature or concentration of reactants or products.

5 0

3 years ago