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2 years ago

which one of the following groups are decomposers a. algae b. protist c. fungi d. green plants e. photosynthetic bacteria

Chemistry

1 answer:

alukav5142 [94]2 years ago

7 0

Answer:c

Explanation:

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Suppose you have just added 100 ml of a solution containing 0.5 mol of acetic acid per liter to 400 ml of 0.5 m naoh. what is th

Tpy6a [65]

$pH = 13.5$

Explanation:

Sodium hydroxide completely ionizes in water to produce sodium ions and hydroxide ions. Hydroxide ions are in excess and neutralize all acetic acid added by the following ionic equation:

$\text{HAc} + \text{OH}^{-} \to \text{Ac}^{-} + \text{H}_2\text{O}$

The mixture would contain

$0.4 \times 0.5 - 0.1 \times 0.5 = 0.15 \; \text{mol}$ of $\text{OH}^{-}$ and
$0.1 \times 0.5 = 0.05 \; \text{mol}$ of $\text{Ac}^{-}$

if $\text{Ac}^{-}$ undergoes no hydrolysis; the solution is of volume $0.1 + 0.4 = 0.5 \; \text{L}$ after the mixing. The two species would thus be of concentration $0.30 \; \text{mol} \cdot \text{L}^{-1}$ and $0.10 \; \text{mol} \cdot \text{L}^{-1}$ , respectively.

Construct a RICE table for the hydrolysis of $\text{Ac}^{-}$ under a basic aqueous environment (with a negligible hydronium concentration.)

$\begin{array}{cccccccc} \text{R} & \text{Ac}^{-}(aq) &+ & \text{H}_2\text{O}(aq) & \leftrightharpoons & \text{HAc}(aq) & + & \text{OH}^{-} (aq)\\ \text{I} & 0.10 \; \text{M} & & & & & &0.30 \; \text{M}\\ \text{C} & -x \; \text{M}& & & & +x \; \text{M}& & +x \; \text{M} \\ \text{E} & (0.10 - x) \; \text{M} & & & & x \; \text{M} & & (0.30 +x) \; \text{M} \end{array}$

The question supplied the <em>acid</em> dissociation constant $pK_a$ for acetic acid $\text{HAc}$ ; however, calculating the hydrolysis equilibrium taking place in this basic mixture requires the <em>base</em> dissociation constant $pK_b$ for its conjugate base, $\text{Ac}^{-}$ . The following relationship relates the two quantities:

$pK_{b} (\text{Ac}^{-}) = pK_{w} - pK_{a}( \text{HAc})$

... where the water self-ionization constant $pK_w \approx 14$ under standard conditions. Thus $pK_{b} (\text{Ac}^{-}) = 14 - 4.7 = 9.3$ . By the definition of $pK_b$ :

$[\text{HAc} (aq)] \cdot [\text{OH}^{-} (aq)] / [\text{Ac}^{-} (aq) ] = K_b = 10^{-pK_{b}}$

$x \cdot (0.3 + x) / (0.1 - x) = 10^{-9.3}$

$x = 1.67 \times 10^{-10} \; \text{M} \approx 0 \; \text{M}$

$[\text{OH}^{-}] = 0.30 +x \approx 0.30 \; \text{M}$

$pH = pK_{w} - pOH = 14 + \text{log}_{10}[\text{OH}^{-}] = 14 + \text{log}_{10}{0.30} = 13.5$

6 0

3 years ago

In 2011, a computer named Watson competed against two humans on a popular television quiz show and won. Watson listened to each

Molodets [167]

Answer:

A computer is made up of wires which is like nerves in our body they send signals throughout our bodies and tell us what to do about a situation. The hard drive of a computer is just like our brain which is the main component of the nervous system it controls involuntary, voluntary, movement and coordination. Also, just like the keys and mouse of a computer we have sensory neurons which pick up what is around us by touch.

Explanation:

6 0

3 years ago

What is absolute zero? A) The temperature at which the particles of matter are at their lowest energy points. B) The temperature

Alja [10]

Answer:

A) The temperature at which the particles of matter are at their lowest energy points.

Explanation:

Absolute temperature refers to the lowest possible temperature. At this state, no heat energy remains in the substance; the energy of the particles are at their lowest energy points.

7 0

3 years ago

A recipe requires 10 grams of salt. According to Weber’s constant for saltiness, which is 1/5, how much more salt must a chef ad

ludmilkaskok [199]

Answer:

2 grams of salt must be added by chef to make the recipe noticeably saltier.

Explanation:

Weber's Law :

$k=\frac{\Delta I}{I}$

Where =

I = Initial stimulus intensity

ΔI = Difference threshold

k = Weber constant

According to Weber’s constant for saltiness , k= $\frac{1}{5}$

Amount of salt required for the recipe , I= 10 g

$\frac{\Delta I}{10 g}=\frac{1}{5}$

$\Delta I = 2 g$

2 grams of salt must be added by chef to make the recipe noticeably saltier.

6 0

3 years ago

A radioactive substance has a half-life of 5 million years. What is the age of a rock in which 25% of the original radioactive a

Phantasy [73]

Answer:

d. 10 million years

Explanation:

These are the options for the question

Choose one answer.

a. 2.5 million years

b. 5 million years

c. 15 million years

d. 10 million years

✓half-life of the radioactive substance= 5 million years

✓ Then for every 5 million years, original radioactive given (100%) percentage is reduced by factor of 1/2.

✓ 1st 5 million year; After the first 5 million years, the original radioactive is reduced as;

(100%) × 1/2 = 50% remains

✓2nd 5 million year: At 10 millions year, the 50% remaining radioactive is reduced by factor of 1/2

(50%) × 1/2 = 25% remains

Hence, at At 10 millions years 25% of the original radioactive atoms remain

6 0

3 years ago