According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

Both 1,2−dihydronaphthalene and 1,4−dihydronaphthalene may be selectively hydrogenated to 1,2,3,4−tetrahydronaphthalene. one of these isomers has a heat of hydrogenation of 101 kj/mol (24.1 kcal/mol), and the heat of hydrogenation of the other is 113 kj/mol (27.1 kcal/mol). match the heat of hydrogenation with the appropriate dihydronaphthalene.

What best discribes the relationship between wavelength and frequency in a electromagnetic wave

What is the empirical formula of a compound that is 50.7% antimony and 49.3% selenium ?