Element Y from group 6A can form two chloride compounds, YCl₂ and YCl₄. When 11.33 g of YCl₂ reacts with excess Cl₂, 19.13 g of YCl₄ is formed. Identify element Y.

An alloy sample has a mass of 57.35 g and 6.022 × 10²³ atoms. Composition analysis shows that 80% of the sample is Ni and 20% is another element. Identify the other element in the alloy.

The composition of gold alloys is described using the karat scale based on mass percentages. Determine the karat number of an alloy made up of 24.4 mol% gold and 75.6 mol% copper. Predict the color of the alloy using the figure below.

Identify the mass % of carbon in Ibuprofen, C₁₃H₁₈O₂.

Consider a compound with the following formula: MBr₂. The percent of bromine is 74.42% by mass. Determine the identity of the metal M.

For the molecule, Alanine, calculate the mass % of N.

Legend:

N → blue

O → red

C → gray

H → white