H2 how many elements?

Which element would you expect to be more metallic?<br> (a) Ca or Rb (b) Mg or Ra (c) Br or I

svlad2 [7]

Explanation:

When we move across a period from left to right then there will occur an increase in electronegativity and also there will occur an increase in non-metallic character of the elements.

As calcium (Ca) is a group 2A element and rubidium (Rb) is a group 1A element. Hence, Rb being an alkali metal is more metallic in nature than calcium (alkaline earth metal).

Both magnesium (Mg) and radium (Ra) are group 2A elements. And, when we move down a group then as the size of element increases so, it becomes easy of the metal atom to lose an electron.

As a result, there occurs an increase in metallic character of the element. Hence, Radium (Ra) is more metallic in nature than magnesium (Mg).

Also, both bromine and iodine are group 17 elements. Since, both of them are non-metals and non-metallic character increases on moving down the group.

Therefore, bromine (Br) is more metallic than iodine.

7 0

3 years ago

As a technician in a large pharmaceutical research firm, you need to produce 250. mL of a potassium dihydrogen phosphate buffer

Reika [66]

Answer:

We will need 147.772 mL of KH2PO4 to make this solution

Explanation:

For this case we can give the following equation:

H2PO4 - ⇄ H+ + HPO42-

With following pH- equation:

pH = pKa + log [HPO42-]/[H2PO4-]

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

-0.16 = log [HPO42-]/[H2PO4-]

10^-0.16 = [HPO42-]/[H2PO4-]

0.6918 = [HPO42-]/[H2PO4-]

Let's say the volume of HPO42-= x then the volume of H2PO4- will be 250 mL - x

Since both have a concentration of 1M = 1 mol /L

If we plug this in the equation 0.6918 = [HPO42-]/[H2PO4-]

0.6918 = x / (250 - x)

0.6918*250 - 0.6918x = x

172.95 = 1.6918x

x = 102.228 mL

The volume of HPO42- = 102.228 mL

Then the volume of H2PO4- = 250 - 102.228 = 147.772 mL

To control this we can plug this in the pH equation

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

7.05= 7.21 + log (102.228 / 147.772) = 7.05

We will need 147.772 mL of KH2PO4 to make this solution

3 0

3 years ago

Which will NOT occur when a light tray ray interacts with a smooth pane of glass?

zhuklara [117]

Answer:

B) diffraction

Explanation:

A smooth pane of glass does not diffract light. A light passing through a smooth pane of glass may be absorbed, reflected or transmitted.

Diffraction only occurs with special types of glasses embedded with a diffraction grating and are called super prisms. Diffraction glasses use a a gradient lens which is able to separate light into all the colors of the rainbow.

Recall that diffraction is the separation of white light into its component wavelengths.

5 0

2 years ago

How does electromagnetism play a role in space

mr_godi [17]

Answer:

Magnets can be used in space. ... One class of magnets, called electromagnets, does need electricity to work.

Explanation:

8 0

3 years ago

Which describes Lithium chloride

Rasek [7]

Answer:

Lithium chloride is a white solid hygroscopic soluble in water.

8 0

3 years ago