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3 years ago

Which gas is used by divers and why

1 answer:

5 0

What they breathe is compressed air. Yes normal air that every one breathes. This is compressed to 200bar and can last for approx. half an hour depending on the diver. What is exhaled is is also the same, namely carbon dioxide.
Sometimes divers mix gases to different ratios to give themselves longer dive times. This is called 'Ni-trox', which means ( Nitrogen/ Oxygen mixture). The gases exhaled are slightly different.

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How many grams of MgO are in 3.500 moles?

borishaifa [10]

(3.500 mol MgO)(40.3044g MgO/1mol MgO)
=141.0654

7 0

3 years ago

How does a buffer resist change in pH upon addition of a strong acid? The strong acid reacts with the strong base in the buffer

MrRa [10]

Answer:

The strong acid reacts with the weak base in the buffer to form a weak acid, which produces few H+ ions in solution and therefore only a little change in pH.

Explanation:

When a strong acid is added to the buffer, the acid dissociates and furnish hydrogen ions which combine with the conjugate of the weak acid, forming weak acid. The weak acid dissociates to only some extent and can furnish only some protons and there is no significant change in the pH.

Hence, option B is correct.

4 0

3 years ago

Which of the following molecules or ions is polar? (20 POINTS)

taurus [48]

For NO3- molecule(fig.1)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NO3 are polar.

2. In the geometry of the molecule bond polarities cancel out each other (since it is a vector) so NO3- ion molecule is non polar

3. Nitrate (NO3-)ion geometry would be trigonal planar

For CCl4 molecule(fig.2)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in CCl4 are polar.

2. It is a completely symmetrical molecule.

3.Carbon is the centre of CCl4 have four covalent bonds and it has no lone pairs. They are all equidistant the C-Cl bond polarities cancel out. So CCl4 molecule is non polar

For NH3 molecule(fig.3)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NH3 molecule are polar.

2. it has a pyramidal structure.

3. the individual N-H bond dipoles don't cancel out. This dipole moment for the molecule indicates that NH3 is a polar molecule

For SF6 molecule(fig.4)

1.F is more electronegative than S. So the bonds are polar.

2. The symmetry of the molecule is symmetrical so that the dipole moments of bonds cancel correspond so the molecule is non-polar.

3. it has octahedral structure

3 0

4 years ago

Which element is the least reactive, Li, Be, Mg, Na?

Oxana [17]

Answers:

Lithium-Li

Beryllium-Be

Magnesium-Mg

Sodium-Na

4 0

3 years ago

What is the mass of 1 atom?

VLD [36.1K]

6.7 mass because 1 atom equals 6.3 but if u add 4 it would be 6.7

6 0

3 years ago