Help—Cecilia wants to measure the thickness of a piece of cardboard. She stacked 10 identical cardboard pieces and used a ruler to measure the thickness of the stack as shown in the figure.

Which of these is the most accurate thickness of a single piece of cardboard?
0.25 cm
0.5 cm
2.5 cm
5 cm

answer: a tank of height h is filled with water and sits on the ground. water squirts from a hole at a height y above the ground and has a range r. for two y values, 0 and h, r is zero. determine the value of y for which the range will be a maximum.

explanation:

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

hcl + naoh → h2o + nacl

explanation:

hcl + naoh → h2o + nacl   is the reaction that is correctly balanced.

however, pcl3 + h2 → ph3 +3hcl, 2ca+ 3cl2 → cacl3, and c5h12 + 5o2 → 5co2 + 6h2o are not correctly balanced.