Freon-11, CCl3F has been commonly used in air conditioners. It has a molar mass of 137.35 g/mol and its enthalpy of vaporization

Answer:

True

Explanation:

Animals have evolved, Charles Darwin proved so during his time and they continue to evolve today based on their environment.

Answer:

• <em>The mystery substance is</em> <u>C. Bromine (Br) </u>

Explanation:

<em>Argon (Ar) </em>is a noble gas. Whose freezing point is -189 °C (very low), thus it cannot be the frozen substance. Also, it is not reactive, thus is would have not reacted with iron. Hence, argon is not the mystery substance.

<em>Scandium (Sc) </em>is a metal from group 3 of the periodic table, thus is will not react with iron. Thus, scandium is not the mystery substance.

Both <em>bromine</em> and <em>iodine</em> are halogens (group 17 of the periodic table).

The freezing point of bromine is −7.2 °C, ​and the freezing point of iodine is 113.7 °C. Thus, both could be solids (frozen) in the lab.

The reactivity of the halogens decrease from top to bottom inside the group. Bromine is above iodine. Then bromine is more reactive than iodine.

Bromine is reactive enough to react with iron. Iodine is not reactive enough to react with iron.

You can find in the internet that bromine vapour over hot iron reacts  producing iron(III) bromide. Also, that bromine vapors are red-brown.

Therefore, <em>the mystery substance is bromine (Br).</em>

Answer:

1) wavelength

2) 1.03 x 10 ^ 4 hz

3) 8.1 x 10 ^4 m

Explanation:

Answer:

A hydrogen bonding is a bond class that is produced from the attraction existing in a hydrogen atom and an oxygen, fluorine or nitrogen atom with a negative charge. This attraction, meanwhile, is known as dipole-dipole interaction and links the positive pole of one molecule with the negative pole of another.

Explanation:

The hydrogen atom, which has a positive charge, is known as the donor atom, while the oxygen, fluorine,  chlorine or nitrogen atom is the bond acceptor atom. In the substance in which they are most effective is in the water.

Hydrogen bonds have only one third of the strength of covalent bonds, but they have important effects on the properties of the substances in which they occur, especially in terms of melting and boiling points in crystal structures.

Answer: -

2.5 mL

Explanation: -

Volume of final solution = 10 mL

Strength of final solution = 10 mg / mL

Amount of drug required = Volume of final solution x strength of final solution

= 10 mL x 10 mg/ mL

= 100 mg.

Strength of supplied drug = 40mg/ mL

Volume of supplied drug required =

= 2.5 mL

Thus to make 10 ml of a 10 mg/ml solution. 2.5 mL will be needed.