Answer:
Kr
Explanation:
The noble gas that is isoelectronic with Br⁻ is krypton.
This is because krypton is the closest noble gas to Br on the periodic table.
Electronic configuration of Bromine is;
2, 8, 18, 7
Br⁻ becomes; 2, 8, 18, 8
Krypton is; 2, 8, 18, 8
Put one thousand becaus it says one thousand :) your welcome
Density of a substance is defined as the mass of the substance divided by the volume.
Density of the substance= 0.242 g cm⁻³
volume of the substance= 2.50 in³
As, 1 in³= 16.39 cm³
So, 2.50 in³= 16.39× 2.50 cm³=40.97 cm³
As ,
Mass=volume ×Density
Mass=40.97 × 0.242
Mass=9.916 g.