What is the standard unit that astronomers use to measure the size of a star

How hydrogen chloride gas is prepared on labrotary by conc sulpheric acid

Citrus2011 [14]

Answer:

It is prepared small amounts of hydrogen cloride for uses in the lab.

It can be "generated in an HCl generator by dehydrating hydrochloric acid with either sulfuric acid or anhydrous calcium chloride."

4 0

3 years ago

Perform the following mathematical operation and express the results to the correct number of significant figures. (0.102 x 0.08

Kobotan [32]

Answer:

2.26

Explanation:

First you should know what are significant figures,

1 . All non - zero digits are significant.

2 . The zero between two non- zero are significant.Ex 302 has 3 significant figures.

3. The zero before the decimal and before any non-zero digit is non significant. Example : 0.003 has only 1 significant figure.

4. The zero after non zero are non - significant . But the zeros after the decimal point are significant.

300 has only 1 significant figure

300.0 has 4 significant figure

The least number of significant figures present in the number should be there in the final answer of the calculation.

Look at the number having minimum significant digits :

It is 3 (every number has 3- significant figures ) So the answer should also contain 3 - significant figures.

$\frac{0.102\times 0.0821\times 273}{1.01}$

First solve the numerator part

$\frac{2.285}{1.01}$

$=2.2635$

Round off this number to 3 significant figures.

Answer is = 2.26

It has 3 - significant digit since all the digits are non-zero.

5 0

3 years ago

When is the next lunar Eclipse and how do they happen?

kondaur [170]

°°The next Lunar Eclipse is on March 23, a Wednesday THIS YEAR - 65 days left!

°° A Lunar Eclipse happens when the moon passes directly behind the earth into its umbra, or, shadow. This can occur only when the sun, Earth and moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a Lunar Eclipse can occur only the night of a full moon. The type and length of an eclipse depends upon the Moon's location relative to its orbital nodes. Isn't that cool?

↑ ↑ ↑ Hope this helps! :D

6 0

3 years ago

The total volume of seawater is 1.5 x 10²¹ L. Seawater contains approximately 3.5% sodium chloride by mass. At that high of a co

garri49 [273]

Answer:

There are $5.408\times 10^{22}$ grams contained in all the seawater in the world.

Explanation:

At first let is determinate the total mass of seawater ( $m_{sw}$ ), measured in grams, in the world by definition of density and considering that mass is distributed uniformly:

$m_{sw} = \rho_{sw}\cdot V_{sw}$

Where:

$\rho_{sw}$ - Density of seawater, measured in grams per liters.

$V_{sw}$ - Volume of seawater, measured in liters.

If $V_{sw} = 1.5\times 10^{21}\,L$ and $\rho_{sw} = 1030\,\frac{g}{L}$ , then:

$m_{sw}=\left(1030\,\frac{g}{L} \right)\cdot (1.5\times 10^{21}\,L)$

$m_{sw} = 1.545\times 10^{24}\,g$

The total mass of sodium chloride is determined by the following ratio:

$r = \frac{m_{NaCl}}{m_{sw}}$

$m_{NaCl} = r\cdot m_{sw}$

Given that $m_{sw} = 1.545\times 10^{24}\,g$ and $r = 0.035$ , the total mass of sodium chloride in all the seawater in the world is:

$m_{NaCl} = 0.035\cdot (1.545\times 10^{24}\,g)$

$m_{NaCl} = 5.408\times 10^{22}\,g$

There are $5.408\times 10^{22}$ grams contained in all the seawater in the world.

8 0

4 years ago

Why is cyanide ion negatively charged?

Bogdan [553]

The cyanide is $CN^{-}$
A carbon atom has 4 valance electrons and nitrogen has 5. Below is a Lewis-dot-structure of cyanide.
:N≡C.
The carbon atom is still one electron short of having a full octet and so it will seize another electron from almost anything, making the cyanide ion negative and whatever it took the electron from it now positive.

8 0

3 years ago