Use this formula to find it

Starting amount = 40g
Half life = 4 days
Time gone = 12 days
Amount left = 40 (1/2)^12/4
= 40 (1/2)^3
= 40 (1/8)
= 5 grams
Plants and animals RE a carbon source during respiration. they take in Oxygen and give out Carbon (IV) oxide as a by product. Combustion of fossil fuels is also source of carbon (IV) Oxide.
Formation of fossils from dead plants and animals is a carbon sink. photosynthesis is also a carbon sink as plants take in carbon (IV) Oxide that is used to make food.
<span>The Three R's: Reduce, Reuse and Recycle. The three R's - reduce, reuse and recycle - all help to cut down on the amount of waste we throw away. They conserve natural resources, landfill space and energy.
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The answer is option e that is e. Iron and magnesium.
Dark silicates have a specific gravity of 3.2 to 3.6 and are composed primarily of silica tetrahedral and iron and magnesium.
Iron and magnesium is a component of dark silicates that have a specific gravity of 3.2 to 3.6.
So the answer is iron and magnesium.
Answer & Explanation:
In physics, a contact force is a force that acts at the point of contact between two objects, in contrast to body forces. Contact forces are described by Newton's laws of motion, as with all other forces in dynamics. Contact force is the force in which an object comes in contact with another object. Contact forces are also direct forces. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car up a hill or kicking a ball or pushing a desk across a room are some of the everyday examples where contact forces are at work. In the first case the force is continuously applied by the person on the car, while in the second case the force is delivered in a short impulse.