I have to turn this in tonight! What is the main center line called on the hockey ice rink?

Why is the development of the game of Hockey as it relates to European countries important even in today's modern
Hockey?
(We spoke about this in class in great detail)

When play stops in the game of hockey, to restart the action what is that called? (Hint: there are several points on the rink)

Which of these metals are magnetic?

Aflask with vinegar in it has a mass of 160 grams. a balloon with baking soda in it has a mass of 40 grams. the balloon is attached to the flask to seal the opening and the vinegar and baking soda mixes. the balloon inflates to a large volume. what will the total mass of the balloon and flask be after the balloon inflates? explain. a) less than 200 grams because the solid baking soda disappears. b) 200 grams, because all the atoms remain in the balloon or flask. c) more than 200 grams because the size of the balloon is so much larger. d) less than 200 grams because gases such as the one in the balloon are lighter than solids and liquids.

While carrying a heavy box up the stairs,you set the box on a step and rest. then you pick up the box and carry it to the top of the stairs. describe these actions in terms of balanced and unbalanced forces acting on the box.