In which of the following examples has a chemical reaction occurred? a .after putting liquid batter into a hot pan, the batter solidifies and begins to turn brown. b .after turning on a blender filled with fruits, the fruit is chopped up and mixed together. c. after taking a tray filled with ice cubes out of the freezer, the cubes begin to melt. d. after adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms