Which one of these reactions is energy released? a all reactions b no reactions c endothermic reactions d exothermic reactions

 The  reaction  that is energy released  is exothermic  reactions (answer D)

  Explanation

Exothermic  reaction  is a chemical reaction  that releases energy  through heat or light.

Example  of exothermic reaction is   combustion reaction  such as  lighting a candle  which produces  carbon dioxide, water and heat.

 Endothermic reaction in  other  hand it  is  a chemical  reaction that  absorb energy  from the surrounding.

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.