Iodine (iodine-potassium iodide) staining distinguishes starch ( a polysaccharide) from monosaccharides, a disaccharides and other polysaccharides. Therefore, a bluish black color is a positive test for starch, and a yellow-ish brown color ( no color change) is a negative test for starch.
We may not see notice it but plate tectonics actually have a "recycle" process. However, scientist reported that it happens in a span of 500 million years. Over the years, the oceanic crusts are pressured to the topmost layer of the mantle causing the oceanic crusts to melt and mix with the Earth's mantle. Such crust blending results to the formation of volcanoes underwater. In time, the said volcanoes would erupt causing the formation of new oceanic and continental crusts.
Answer:
The yield of the product in gram is 
Explanation:
Given that:
the molecular mass weight of the product = 96.2 g/mol
the molecular mass of the reagent (3S)-2,2,-dibromo-3,4-dimethylpentane is 257.997 g
given that the millimoles of the reagent = 2,7 millimoles = 
We know that:
Number of moles = mass/molar mass
Then:
mass = 0.697
Theoretical yield = (number of moles of the product/ number of moles of reactant) × 100
i.e
Theoretical yield = 
where;
and 
Theoretical yield = 
Given that the theoretical yield = 100%
Then:
where,
= derived weight of the product
the molecular mass of the derived product
the molecular mass of the reagent
= weight in a gram of the reagent
The answer is <span>1.63 × 1024 atoms Fe.
</span>
Avogadro's number is the
number of units (atoms, molecules) in 1 mole of substance:
<span>6.023 × 10²³ atoms per 1 mole
</span>So, how many atoms are per 2.70 moles:
6.023 × 10²³ atoms : 1 mole = x : 2.70 moles
x = 6.023 × 10²³ atoms * 2.70 moles : 1 mole
x = 16.3 × 10²³ = 1.63 × 10 × 10²³ = 1.63 × 10²⁴ atoms
Nitrous acid<span> dissociates as follows:
</span>
HNO₂(s) ⇄ H⁺(aq) + NO₂⁻(aq)
According to the equation, an acid constant has the following form:
Ka = [H⁺] × [NO₂⁻ ] / [HNO₂]
From pH, we can calculate the concentration of H⁺ and NO₂⁻:
[H⁺] = 10^-pH = 10^-2.63 = 0.00234 M = [NO₂⁻]
Now, the acid constant can be calculated:
Ka = 0.00234 x 0.00234 / 0.015 = 3.66 x 10⁻⁴
And finally,
pKa = -log Ka = 3.44
