Why are shadows shorter around noon?
Make sure you give a full, detailed answer, not just one sentence.

Explanation:

so for this one u need to remember this equation and use it to find out moles= mass /mr . Mr of helium is 4

so moles= mass /mr

=100/4

=25 moles

hope this make sense:)

The reactant necessary for a combustion reaction is oxygen.

(option D).

Combustion is a chemical reaction that occurs when a substance reacts with oxygen, producing heat and light. In order for combustion to take place, three elements are needed: fuel, heat, and oxygen.
Fuel is the substance that undergoes combustion, such as gasoline, wood, or methane. Heat is the energy required to initiate and sustain the reaction. Lastly, oxygen is the reactant that combines with the fuel, allowing it to burn and release energy.
When a combustion reaction occurs, the fuel and oxygen combine to form carbon dioxide (option C) and water (option A). This process is exothermic, meaning it releases energy in the form of heat and light.
For example, when wood is burned in the presence of oxygen, it undergoes combustion. The heat from a match or a spark provides the necessary activation energy to start the reaction. Oxygen from the air combines with the carbon in the wood, producing carbon dioxide and releasing energy in the form of heat and light.
In summary, oxygen is the reactant necessary for a combustion reaction. It combines with the fuel and releases energy in the form of heat and light.

(option D).

For more such questions on combustion reaction

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Answer:

Acoustic survey data can help inform scientists about the locations of the rainforest with the highest biodiversity. ... By working with these companies, The Nature Conservancy can help inform them of where they might try to create wildlife corridors or connected habitats on their lands

Answer:

Both hydrogen and oxygen gases exist as diatomic (“two-atom”) molecules. These molecules are the reactants in the reaction

Explanation:

:)

Answer:

well I think it's false

I hope it helps

have a nice day

#Captainpower

Answer:

Smaller

Explanation:

I took the test

Answer:

1. A

2. C

3. B

4. D

5. D

6. B

Explanation:

I'm not quiet sure on 5 but I'm pretty sure its correct

Answer:

A maybe I said maybe hope help

Explanation:

..

Answer:

steel, plastics

Hope it helps!

Answer:

(a) pH=4.0

(b) pH=8.3

Explanation:

Hello there!

In this case, since the pH is understood as the potential of the hydrogen in an aqueous solution, and we can calculate it is as follows:

[tex]pH=-log([H^+])[/tex]

We simply need to plug in the concentrations on each question as shown below:

(a)

[tex]pH=-log(1x10^{-4})\\\\pH=4[/tex]

(b)

[tex]pH=-log(5x10^{-9})\\\\pH=8.3[/tex]

Regards!

Answer:

13) What common form of energy (not including kinetic or potential) is not included in the “Energy Symbols” key that would normally be present in these examples?

1) Sound Energy

2) Magnetic Energy

14)Look carefully at each of the four systems shown above. Knowing what we have discussed about energy conversions, identify (list) at least three different places where this form of energy (sound) should be “produced”.

1) When you open the water tap, in the turbine and the sound of the light bulb.

2) In the light bulb

3) The sound of the kettle, the turbine and when water is boiling.

4) The movement of the wheel of the bicycle, the turbine and the light bulb.

Answer:

Explanation:

Ba(OH)₂ (aq) + 2HCl (aq) --> 2H₂O (l) + BaCl₂ (aq)

171 g                    2 x 36.5 g     2 x 18 g

73 g of HCl reacts with 171 g of Ba(OH)₂

125 g HCl reacts with 171 x 125 / 73 g of Ba(OH)₂

= 292.8 g of  of Ba(OH)₂

Ba(OH)₂  available is 250 g , so it is the limiting reagent .

171 g of Ba(OH)₂ forms 36 g of water

250 g of Ba(OH)₂ forms 36 x 250 / 171 g of water

= 52.63 g of water.

Answer:

0 kJ/mol

Explanation:

Step 1: Given data

Step 2: Calculate the Gibbs free energy change (ΔG)

We can calculate the Gibbs free energy change using the following expression.

ΔG = ΔH - T × ΔS

ΔG = 27 kJ/mol - 300 K × 0.09 kJ/mol.K = 0 kJ/mol

Since ΔG = 0 kJ/mol, the process in not spontaneous nor non-spontaneous.

Answer:

8 meters per second per second

Explanation:

Newton's second law: [tex]f=ma[/tex], force = mass multiplied by acceleration.

Therefore 56 / 7 = acceleration = 8

Answer:

b

Explanation:

Radar uses radio, and the siren uses sound waves, but both exhibit the Doppler effect. Therefore, option (C) is correct.

Radar operates by emitting radio waves and measuring the reflected waves to detect objects and determine their velocity. On the other hand, an approaching siren emits sound waves that propagate through the air.

Both radar and an approaching siren exhibit the Doppler effect. The Doppler effect is the change in frequency or pitch of waves (sound or electromagnetic) when the source of the waves and the observer are in relative motion. In the case of radar, the Doppler effect is used to measure the velocity of objects based on the frequency shift of the reflected radio waves. Similarly, the Doppler effect is observed with an approaching siren as the sound waves compress and the frequency appears higher as the source approaches the listener.

Therefore, both radar and an approaching siren differ in the type of waves they use (radio waves vs. sound waves), but they share the characteristic of exhibiting the Doppler effect.

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Answer: Wind, in climatology, the movement of air relative to the surface of the Earth. Winds play a significant role in determining and controlling climate and weather.

Answer:

Hail is a type of precipitation, or water in the atmosphere. Hail is formed when drops of water freeze together in the cold upper regions of thunderstorm clouds. These chunks of ice are called hailstones. Most hailstones measure between 5 millimeters and 15 centimeters in diameter, and can be round or jagged.

Explanation:

Answer:

V = 1.95 L.

Explanation:

Hell there!

In this case, according to the following reaction between sodium metal and water:

[tex]2Na+2H_2O\rightarrow 2NaOH+H_2[/tex]

We can realize that the moles of hydrogen can be calculated by using the initial mass of sodium, its atomic mass (23.0 g/mol) and the 2:1 mole ratio of sodium to hydrogen to obtain:

[tex]4.00gNa*\frac{1molNa}{23.0gNa} *\frac{1molH_2}{2molNa}=0.0870molH_2[/tex]

Finally, we calculate the volume of hydrogen by using the ideal gas equation whereas the pressure is 1 atm and the temperature 273.15 K according to the STP conditions:

[tex]PV=nRT\\\\V=\frac{nRT}{P}\\\\V=\frac{0.0870mol*0.08206\frac{atm*L}{mol*K}*273.15 K}{1 atm}\\\\V=1.95L[/tex]

Regards!

Answer:

V2 = 159.48 mL

Explanation:

Given the following data;

Initial volume = 200 mL

Initial temperature = 28°C

Final temperature = -33°C

To find the final volume, V2, we would use Charles law;

First of all, we would convert the temperature in Celsius to Kelvin.

Mathematically, it is given by the formula;

Kelvin = 273 + C

Substituting into the equation, we have;

Initial temperature, T1:

Kelvin = 273 + 28

Kelvin = 301K

Initial temperature, T1:

Kelvin = 273 - 33

Kelvin = 240K

To find new volume V2, we would use Charles' law.

Charles states that when the pressure of an ideal gas is kept constant, the volume of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Charles is given by;

[tex] VT = K[/tex]

[tex] \frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}[/tex]

Where;

V1 and V2 represents the initial and final volumes respectively.

T1 and T2 represents the initial and final temperatures respectively.

[tex] \frac{V1}{T1} = \frac{V2}{T2}[/tex]

Making V2 as the subject formula, we have;

[tex] V_{2}= \frac{V1}{T1} * T_{2}[/tex]

[tex] V_{2}= \frac{200}{301} * 240[/tex]

[tex] V_{2}= 0.6645 * 240 [/tex]

V2 = 159.48 mL

[tex]methane \: reacts \: with \: oxygen [/tex]

CH4 + 2O2 → CO2 + 2H2O.

Step-by-step explanation

L.H.S.

C = 1, H = 4, O = 2×2 = 4.

R.H.S

C = 1, O = 2, H = 2×2= 4, O = 2.

Answer:

decomposers

Explanation:

I'm not sure weather your supposed to create an actual experiment or write a paper. If an experiment, test certain acids to see which one can decompose plastics the fastest and determine which one can be spread through the oceans to melt down plastic. If a paper, discuss the idea of genetically modified fish. Some animals in the wild have the ability to eat pollution (wrappers, bottles, ect.), so mutating fish such as bottom feeders to be able to do the same would easily rid the water of pollution and make for one interesting of a paper! hope this sort of helped!

Answer:

0.333J/g°C is the specific heat of the metal

Explanation:

The heat that the metaal gives is equal to the heat that water is absorbing. The equation is:

S(metal)*ΔT(metal)*Mass(metal) = S(H2O)*ΔT(H2O)*Mass(H2O)

Where S is specific heat, ΔT is change in temperature and mass the mass in grams of the metal and water.

Replacing:

S(metal)*(100.0°C-27.2°C)*125.0g = 4.184J/g°C*(27.2°C-24.3°C)*250.0g

S(metal) = 4.184J/g°C*(27.2°C-24.3°C)*250.0g / (100.0°C-27.2°C)*125.0g

S(metal) = 0.333J/g°C is the specific heat of the metal

Answer:

22.4 L

hope it will help you

Answer:

Explanation:

b

Answer:

Clean a platinum or nichrome (a nickel-chromium alloy) wire by dipping it into concentrated hydrochloric acid and then holding it in a hot Bunsen flame. Repeat this until the wire produces no color in the flame.

Answer:

Atomic nuclei would fly apart

Explanation: