I answered that in your last question refer to your answer in section 2
The correct answer is cyanate.
The polyatomic ion with the formula CN⁻ is called cyanate. A polyatomic ion has two or more atoms bonded together.
CN⁻ contains the cyano functional group wherein a carbon atom forms a triple-bond to a nitrogen atom. CN⁻ is a polyatomic anion that is present in inorganic compounds.
Answer:
The mass of 10 cm³of a 0.4 g/dm³ solution of sodium carbonate is 0.004 grams
Explanation:
The question is with regards to density calculations
The density of the given sodium carbonate solution, ρ = 0.4 g/dm³
The volume of the given solution of sodium carbonate, V = 10 cm³ = 0.01 dm³


Therefore, we have;

The mass, "m", of the sodium carbonate in = ρ×V = 0.4 g/dm³ × 0.01 dm³ = 0.004 g
The mass of 10 cm³ (10 cm³ = 0.01 dm³) of a 0.4 g/dm³ solution of sodium carbonate, m = 0.004 g.
There are 6.022145E+23 atom per one mole.