Question 13 A chemistry student must write down in her lab notebook the concentration of a solution of sodium hydroxide. The concentration of a solution equals the mass of what's dissolved divided by the total volume of the solution. Here's how the student prepared the solution:
The label on the graduated cylinder says:

Empty weight = 2.2g
She put some solid sodium thiosulfate into the graduated cylinder and weighed it. With the sodium thiosulfate added, the cylinder weighed 19.440g. She added water to the graduated cylinder and dissolved the sodium thiosulfate completely. Then she read the total volume of the solution from the markings on the graduated cylinder. The total volume of the solution was 50.29 mL.

What concentration should the student write down in her lab notebook? Be sure your answer has the correct number of significant digits.

0.3428 g/mL is the concentration that student will write in her notebook.

Explanation:

Mass of the empty graduated cylinder, w = 2.2 g

Mass of sodium thiosulfate and graduated cylinder ,w'= 19.440 g

Mass of sodium thiosulfate : W

= w' - w = 19.440 g - 2.2 g = 17.24 g

Volume of the solution after adding water to the graduate cylinder with sodium thiosulfate = V

V = 50.29 mL

According to question :

Concentration of the solution :

0.3428 g/mL is the concentration that student will write in her notebook.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

the answer is c i believe