5 grams of NaHCO3 was added to 50 cm3 of 1.5 mol dm-3 hydrochloric acid, causing the temperature to decrease by 6.8 K. What is t

A total of 0.0222 moles of NaOH are necessary to react with NH4F. \nBased on the reaction NH4F + NaOH --> NaF + NH3 + H2O, we start with: \nMass of NH4F = 0.821 g, NaOH concentration = 1 M, volume of NaOH = 25 mL. \nTo find moles: moles of NaOH = (CV)/1000. Thus, moles of NaOH = (1 * 25)/1000 = 0.025 moles of NaOH used. \nThe molar mass of NH4F is 37 g/mol, making moles of NH4F = 0.821 / 37 = 0.0222 moles. \nThis shows that NaOH is in excess, with 0.025 - 0.0222 = 0.0028 moles of NaOH remaining. Hence, 0.0222 moles of NaOH are needed to react with NH4F.

The electronic configuration of an atom details how electrons are organized across various shells and sublevels.

There are four categories of sublevels: s, p, d, and f. Each of these sublevels contains orbitals, which are regions with a high likelihood of containing an electron, with each orbital capable of holding a maximum of 2 electrons.

As a result,

s-sublevel possesses 1 orbital, allowing for a maximum of 2 electrons.

p-sublevel has 3 orbitals, accommodating a maximum of 6 electrons.

d-sublevel encompasses 5 orbitals, permitting a maximum of 10 electrons.

f-sublevel includes 7 orbitals, with a maximum of 14 electrons.

Therefore, the ascending order of sublevels based on the maximum number of electrons they can hold is:

s < p < d < f