To decrease the power used:

Why can’t you see the stars very well at night like you could 50 years ago

Elenna [48]

Answer:Artificial light from cities has created a permanent "skyglow" at night, obscuring our view of the stars. Here's their map of artificial sky brightness in North America, represented as a ratio of "natural" nighttime sky brightness. In the black areas, the natural night sky is still (mostly) visible.

Explanation:

6 0

2 years ago

A 453 g piece of glass at 25.7∘C is left outside on a sunny day. How much heat must the glass absorb from the sun in order to re

Tju [1.3M]

Answer:

Q = 5555.6J

Explanation:

Mass of glass piece, m = 453g

initial temperature = 25.7°C

temperature to be attained = 40.3°C

⇒change in temperature, Δt = 40.3 - 25.7 = 14.6°C

specific heat of glass, s = 0.840J/g°C

Heat absorbed, Q = msΔt

⇒Q = 453×0.840×14.6 = 5555.592J

⇒<u>Q = 5555.6J</u> (rounded to the nearest tenth)

7 0

3 years ago

Consider the reaction. 2 Pb ( s ) + O 2 ( g ) ⟶ 2 PbO ( s ) An excess of oxygen reacts with 451.4 g of lead, forming 367.5 g of

Art [367]

Answer : The percent yield of the reaction is, 75.6 %

Solution : Given,

Mass of Pb = 451.4 g

Molar mass of Pb = 207 g/mole

Molar mass of PbO = 223 g/mole

First we have to calculate the moles of Pb.

$\text{ Moles of }Pb=\frac{\text{ Mass of }Pb}{\text{ Molar mass of }Pb}=\frac{451.4g}{207g/mole}=2.18moles$

Now we have to calculate the moles of $PbO$

The balanced chemical reaction is,

$2Pb(s)+O_2(g)\rightarrow 2PbO(s)$

From the reaction, we conclude that

As, 2 mole of $Pb$ react to give 2 mole of $PbO$

So, 2.18 mole of $Pb$ react to give 2.18 mole of $PbO$

Now we have to calculate the mass of $PbO$

$\text{ Mass of }PbO=\text{ Moles of }PbO\times \text{ Molar mass of }PbO$

$\text{ Mass of }PbO=(2.18moles)\times (223g/mole)=486.1g$

Theoretical yield of $PbO$ = 486.1 g

Experimental yield of $PbO$ = 367.5 g

Now we have to calculate the percent yield of the reaction.

$\% \text{ yield of the reaction}=\frac{\text{ Experimental yield of }PbO}{\text{ Theoretical yield of }PbO}\times 100$

$\% \text{ yield of the reaction}=\frac{367.5g}{486.1g}\times 100=75.6\%$

Therefore, the percent yield of the reaction is, 75.6 %

3 0

3 years ago

The diameter of carbon atom is 0.000000000 154m. What is the number expressed in scientific notation

kogti [31]

1.54×10 −10

one and fifty four-hundreths times ten to the power of negitiive 10

7 0

3 years ago

Read 2 more answers

Which type of mixture can be separated using magnetism?

Sergeu [11.5K]

Answer: The correct option is heterogeneous mixture whose components are attracted differently to a magnet.

Explanation: There are two types of mixtures:

1) Homogeneous mixtures: In these mixtures, the particles are uniformly distributed throughout the mixture. These particles cannot be separated.

2) Heterogeneous Mixtures: These are the mixtures where the particles are visible separated and are not-uniformly distributed. These particles can be separated easily.

If magnet is used to separate the components of a mixture, the heterogeneous mixtures will only get separated.

To separate the components by a magnet, the components of a mixture should attract the magnet differently. One component should attract the magnet and another should not. Hence, they can be easily separated.

5 0

2 years ago