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3 years ago

A student uses an indicator to measure the pH of a solution. The indicator shows a pH of 7. What must be true of this solution?

2 answers:

8 0

A pH of 7 is known as "natural"

A pH below 7 is an acid

A pH above 7 is a base

Acids give up hydrogen ions, shown as H+
Bases accept H+, hydrogen ions.

Equilibrium is when a chemical reaction doesn't favor the reactants or products and can go in reverse.
pH of 7 are related to Equilibrium.

With the info I have given you, it's obviously not one of the last 2 you listed.

pH measures the alkalinity and acidity of a solution by the Hydrogen ions, H+. Therefore, the solution has to have Hydrogen ions to react/be measured by the pH paper.

Therefore, your answer is the 2nd statement.
The solution has equal amounts of hydronium ions and hydroxide ions.

zloy xaker [14]3 years ago

4 0

Answer:

The solution has equal amounts of hydronium ions and hydroxide ions.

Explanation:

From the very beginning it is clear that answer choices 3 and 4 are incorrect, as a pH of 7 means it is neutral.

The pH of anything being 7 (neutral) means it is neither an acid (1-6) nor a base (8-14).

This essentially levels things out meaning that there will be an equal amount.

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Two conducting spheres are mounted on insulating rods. They both carry some initial electric charge, and are far from any other

natka813 [3]

The question is incomplete. The complete question is :

Two conducting spheres are mounted on insulating rods. They both carry some initial electric charge, and are far from any other charge. Their charges are measured. Then, the spheres are allowed to briefly touch, and the charge in one of them (sphere A) is measured again. These are the measured values:

a). Before contact:

Sphere A = 4.8 nC

Sphere B = 0 nC

What is the charge on sphere B after contact, in nC?

b). Before contact:

Sphere A = 2.9 nC

Sphere B = -4.4 nC

What is the charge on sphere B after contact, in nC?

Solution :

It is given that there are two spheres that are conducting and are mounted on an insulating rods which carry a initial charge and they are briefly touched and then one of the charge is measured.

Here the charge becomes divided when both the spheres are connected and then removed.

a). charge after they are charged

$Q = \frac{q_1+q_2}{2}$

$Q = \frac{4.8+0}{2}$

= 2.4 nC

b). The charge is

$Q = \frac{q_1-q_2}{2}$

$Q = \frac{2.9-4.4}{2}$

= -0.75 nC

6 0

3 years ago

State and prove bessel inequality

maria [59]

Statement :- We assume the orthagonal sequence ${{\{\phi\}}_{1}^{\infty}}$ in Hilbert space, now ${\forall \sf \:v\in \mathbb{V}}$ , the Fourier coefficients are given by:

${\quad \qquad \longrightarrow \sf a_{i}=(v,{\phi}_{i})}$

Then Bessel's inequality give us:

${\boxed{\displaystyle \bf \sum_{1}^{\infty}\vert a_{i}\vert^{2}\leqslant \Vert v\Vert^{2}}}$

Proof :- We assume the following equation is true

${\quad \qquad \longrightarrow \displaystyle \sf v_{n}=\sum_{i=1}^{n}a_{i}{\phi}_{i}}$

So that, ${\bf v_n}$ is projection of ${\bf v}$ onto the surface by the first ${\bf n}$ of the ${\bf \phi_{i}}$ . For any event, ${\sf (v-v_{n})\perp v_{n}}$