Read each description in the first column of the table below. if any chemical element with atomic number of 92 or less matches the description, check yes and enter the chemical symbol of an element that matches. otherwise check no in the second column. descriptiondoes any element match the description? if you checked yes, give the symbol of an element that matches. an element in period 3 and group 2a. yes

All element match the description

Read each description in the first column of the table below. if any chemical element with atomic number of 92 or less matches the description, check yes and enter the chemical symbol of an element that matches. Otherwise check no in the second column.

Description, does any element match the description?, If you checked yes, give the symbol of an element that matches.

Grade:  9

Subject:  chemistry

Chapter:  Periodic Table of the Elements

Keywords:  A transition element, element in period 3, element in group 2a, element, the chemical symbol

  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-

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.