Is Air a Mixture?

Correct Answer: There are approximately 6 trillion miles in a light-year, so the distance we need to go is 6 trillion miles / light-year times 4 light-years is equal to 24 trillion miles So, this whole would take 12 billion hours There are 24 hours a day and 36525 days per year, so this time in years is 137 thousand years

Correct Answer: higher frequency

Explanation:

As the frequency of sound is higher, women have shriller voices than men.

The shrillness or pitch of a sound is determined by its frequency. The higher the pitch shriller the voice. As the sounds produced by vocal cords of women are higher than men so women have shriller voices than men. Because their vocal cord is of smaller size. As their vocal cord is more stretched than men's.

Correct Answer: 30 m/s

Explanation:

The interval between object pass the same point is 4 sec.

That means in 2 sec, object reaches the top and in next 2 sec, it again reaches the same point.

By the info given, we can find the velocity of that point by using : v=u+(-gt)

0= u - 10×2

u = 20

Then the velocity at 25m is 20m/sec.

so the initial velocity is

$$\begin{gathered} - v 2 = u 2 + ( - 2 gh ) \\ 400 = u 2 - 2 x 10 x 25 \\ u 2 = 900 \\ = > u = 30 m / s \end{gathered}$$

Correct Answer: capillary action phenomenon

Explanation:

The absorption of ink by blotting paper involves capillary action phenomenon because the blotting paper is a thin and a smooth paper which allows a little thicker liquids like ink to absorb.

Correct Answer: 30000 deg Cent

Explanation:

Lightning is extremely hot ? a flash can heat the air around it to temperatures five times hotter than the sun?s surface. This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.

Lightning heats the surrounding air to about 30,000 degrees Centigrades.

Correct Answer: D

Explanation:

To complete the vertical loop, the minimum speed required at the lowest point  = 5 g R.

Correct Answer: All the above

Explanation:

Processes that require or give off heat will be limited to changes of state, known as phase changes, and changes in chemical constitution, or chemical reactions. Changes of state involve a solid melting, a liquid freezing, a liquid boiling or a gas condensing.

 

An exothermic process is one that gives off heat, which is transferred to the surroundings. An endothermic process is a reaction which heat has to be supplied to the system from the surroundings.

 

Here in all the given options, heat is taken away from them to change there phase. 

Liquid to Solid --- Freezing

Gas to Liquid --- Condensation

Gas to Solid --- Deposition 

are all examples of exothermic processes.

 

Correct Answer: Pyranometer

Explanation:

Solar radiation instruments may be produced to measure different types of solar energy. When sunlight encounters the Earth's atmosphere, some of it is absorbed or scattered by water vapor, aerosols, clouds, and other air molecules. The radiation which penetrates to the Earth's surface is termed direct solar radiation.

 

A thermopile pyranometer is a type of actinometer used for measuring solar radiation on a planar surface and it is designed to measure the solar radiation flux density (W/m2) from the hemisphere above within a wavelength range 0.3 ?m to 3 ?m.

Correct Answer: P1V1 = P2V2

Explanation:

Ideal Gas Law ::

The Combined gas law or General Gas Equation is obtained by combining Boyle's Law, Charles' Law, and Gay-Lussac's Law. It shows the relationship between the pressure, volume, and temperature for a fixed mass (quantity) of gas:

P 1 V 1 T 1 = P 2 V 2 T 2

 

Hence, the Boyle's law P1V1 = P2T2, relates to ideal gas equation.

Correct Answer: Hydrogen

Explanation:

Entropy is a measure of disorder . It will be maximum in gases followed by liquids and least in solids.

 

Hence, here the gas is only hydrogen and it has the highest entropy.