Answer:
Tech A is right.
Explanation:
Its the ability of quartz crystal that if we apply a mechanical stress on them by an applied force then they can produce the electricity or voltage. This phenomenon of producing electricity by squeezing a crystal is termed as piezoelectricity or a piezoelectric effect.
Answer:
The value is 
Explanation:
From the question we are told that
The diameter of the pupil is 
The distance of the page from the eye 
The wavelength is 
The refractive index is 
Generally the minimum separation of adjacent dots that can be resolved is mathematically represented as
![y = [ \frac{1.22 * \lambda }{d_p * n_r } ]* d](https://tex.z-dn.net/?f=y%20%20%3D%20%5B%20%5Cfrac%7B1.22%20%2A%20%20%5Clambda%20%7D%7Bd_p%20%2A%20n_r%20%7D%20%5D%2A%20d)
![y = [ \frac{1.22 * 500 *10^{-9} }{4.2 *10^{-3} * 1.36} ]* 0.29](https://tex.z-dn.net/?f=y%20%20%3D%20%5B%20%5Cfrac%7B1.22%20%2A%20%20500%20%2A10%5E%7B-9%7D%20%7D%7B4.2%20%2A10%5E%7B-3%7D%20%2A%201.36%7D%20%5D%2A%200.29)

Helium is lighter than air from the lungs.
Explanation:
A balloon filled with the air from lungs will sink to the ground but a balloon filled with Helium floats because helium is lighter than air.
Air is a mixture of many gases.
The air from the lungs is predominantly made up of carbon dioxide and water vapor.
- Gram per mole of carbon dioxide is 44. Water vapor is 18.
- Compared to helium which is 4, we see that the gas is lighter.
- Since the gas is lighter, it will float in air.
- The main component of air around us is nitrogen gas with a gram per mole of 28.
- A balloon filled with more of air from the lungs weigh more than that will filled air around and even far more than helium gas.
- This will cause a helium filled balloon to float.
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The culture that gave the visiting Europeans eyeglasses and silk fabric was the Chinese civilization. The Chinese invented eyeglasses over a 1,000 years ago<span>, according to British scientist and historian Sir Joseph Needman. By the time Marco Polo arrived in China around 1270, eyeglasses (which he mentions in his accounts) were widely used in Chinese upper class. On the other hand, s</span>ilk has been used by the Chinese for approximately 5,000 years.<span> The earliest evidence of silk dates back to around 4,000-3,000 BC in Shanxi province, where a culture silk cocoon was found.</span>