15. D is correct, exothermic reactions release heat
I am not sure about 16
Given :
A 250 ml beaker weighs 13.473 g .
The same beaker plus 2.2 ml of water weighs 15.346 g.
To Find :
How much does the 2.2 ml of water, alone, weigh .
Solution :
Now, mass of water is given by :
Therefore , mass of 2.2 ml of water alone is 1.873 g .
Hence , this is the required solution .
The grams of oxygen that are required to produce 1 mole of H₂O is 16 g ( answer B)
<u><em> calculation</em></u>
2 CH₄ + 2NH₃ +3 O₂ → 2HCN + 6H₂O
step 1: use the mole ratio to find moles of O₂
from equation above the mole ratio of O₂: H₂O is 3:6 therefore the moles of O₂ = 1 mole x3/6 =0.5 moles
step 2: find mass of O₂
mass= moles x molar mass
from periodic table the molar mass of O₂ = 16 x2= 32 g/mol
mass O₂ = 0.5 moles x 32 g/mol = 16 g (answer B)
Norepinephrine<span> (</span>NE<span>), also called </span>noradrenaline<span> (</span>NA<span>) or </span>noradrenalin<span>, is an </span>organic chemical<span> in the </span>catecholamine<span> family that functions in the </span>brain<span> and </span>body<span> as a </span>hormone<span> and </span>neurotransmitter. The name "noradrenaline," derived from Latin roots meaning "at/alongside the kidneys," is more commonly used in the United Kingdom; in the United States, "norepinephrine," derived from Greek roots having that same meaning, is usually preferred.<span> "Norepinephrine" is also the </span>international nonproprietary name<span> given to the </span>drug.<span>Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as </span>noradrenergic<span>.</span>
