Answer:
in 6.0 E3 g of blood at a concentration of 0.62 ppm there are 3.5g of lead content
Explanation:
- blood density: 1.06 g/L
- ppm ≡ mg Pb / L blood
⇒ V blood = 6.0E3gblood * L / 1.06gblood = 5660.37 L blood
<u> mass of lead:</u>
⇒ 5660.37 L blood * 0.62 mg Pb / L blood * 0.001 g / mg
⇒ mass = 3.509 g of lead
Answer:
Greenhouse gases absorb some of the energy and trap it in the lower atmosphere. Less heat radiates into space, and Earth is warmer. Many greenhouse gases occur naturally. Carbon dioxide, methane, water vapor, and nitrous oxide are naturally present in Earth's atmosphere. Since some of the extra energy from a warmer atmosphere radiates back down to the surface, Earth's surface temperature rises.
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Answer:
B. materials change their properties.
Explanation:
In a chemical change, materials often change their properties because a re-arrangement of atoms takes place.
A chemical change is one in which new kind of matter is formed.
It is always accompanied by energy changes.
- Chemical changes are not reversible.
- They lead to the production of new kinds of matter
- It involves mass changes
- Requires considerable amount of energy
