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3 years ago

I NEED HELP PLEASE! THIS IS HARD FOR ME!!

Chemistry

1 answer:

KonstantinChe [14]3 years ago

7 0

Answer:

it should be D! hopes this helps

from all the layer the fossil cant disappear so not C and cNf decrease because there are to many layers so not a but it could be B but d seems to make more sense

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Jerry designed a coat that he thinks could keep people dry during a thunderstorm. He created a prototype that looks just like hi

AlekseyPX

Answer:

The next step is prototype testing

Explanation:

The stages of the design process are;

1) Situation analysis

Paper based research is conducted on the situation to obtain the situation parameters

2) Brief writing

With the situation analysis developed above, the brief of the current situation is put down on paper

3) Problem research

The problem is researched and experimented on with the development of a paper based proof of the possible concept

4) Specification writing

The specifications of the problem are outlined

5) List the possible solutions

The possible solutions are brainstormed and listed

6) Preferred solution selection

The preferred solution is selected based on the constraints in the situation

7) Create working drawing/plan

The working design drawing of the selected solution or concept is completed and evaluated for applicability

8) Building of a prototype

The design is converted into a prototype which is a model of the actual solution

9) Testing of the prototype

The prototype is tested for functionality, for ability to work in the intended situation and/or in the intended system

10) Report writing

A report is made on the outcome of the tests for review before production

Therefore, after the prototype is created, stage 8, the next step is the testing of the prototype stage 9.

5 0

3 years ago

What can bond or join together to form molecules?

ioda

Answer:

Atoms.

They come together so they can form molecules (because of their electrons)

It becomes a covalent bond

Explanation:

5 0

3 years ago

Read 2 more answers

Why do scientists use scientific notation to represent very small and large numbers?

sergij07 [2.7K]

Answer:

to simplify the number by using fewer digits

Explanation:

6 0

3 years ago

During a titration, the pH of an analyte solution containing HA(aq) is 3.92 and the ratio of [A–]/[HA] is 0.41. What is the Ka o

Solnce55 [7]

Answer:

$Ka=4.71x10^{-4}$

Explanation:

Hello there!

In this case, according to the Henderson-Hasselbach equation, it is possible to write:

$pH=pKa+log(\frac{[A^-]}{[HA]} )$

Next, since we are given the pH and the [A–]/[HA] ratio, we can solve for the pKa as shown below:

$pKa=pH-log(\frac{[A^-]}{[HA]} )$

Now, we plug in the values to obtain:

$pKa=3.92-log(0.41 )\\\\pKa=3.33$

Next, Ka is:

$Ka=10^{-pKa}=10^{-3.33}\\\\Ka=4.71x10^{-4}$

Best regards!

3 0

3 years ago

A student has 70.5 mL of a 0.463 M aqueous solution of sodium bromide. The density of the solution is 1.22 g/mL. Find the follow

AleksandrR [38]

Answer:

a.) 86.01 g.

b.) 3.36 g.

c.) 0.394 m ≅ 0.40 m.

d.) 4.77%.

e.) 3.9%.

Explanation:

a.) mass of the solution:

The density of the solution is the mass per unit volume.

∵ Density of solution = (mass of solution)/(volume of the solution).

∴ Mass of the solution = (density of solution)*(volume of the solution) = (1.22 g/mL)*(70.5 mL) = 86.01 g.

b.) grams of sodium bromide :

Molarity (M) is defined as the no. of moles of solute dissolved per 1.0 L of the solution.

∵ M = (no. of moles of NaBr)/(Volume of the solution (L))

∴ no. of moles of NaBr = M*(Volume of the solution (L)) = (0.463 M )*(0.0705 L) = 0.0326 mol.

∵ no. of moles of NaBr = (mass of NaBr)/(molar mass of NaBr)

∴ mass of NaBr = (no. of moles of NaBr)*(molar mass of NaBr) = (0.0326 mol)*(102.894 g/mol) = 3.36 g.

c.) molality of the solution:

Molality (m) is defined as the no. of moles of solute dissolved per 1.0 kg of the solvent.

∵ m = (no. of moles of NaBr)/(mass of the soluvent (kg))

no. of moles of NaBr = 0.0326 mol,

mass of solvent = mass of the solution - mass of NaBr = 86.01 g - 3.36 g = 82.65 g = 0.08265 kg.

∴ m = (no. of moles of NaBr)/(mass of the soluvent (kg)) = (0.0326 mol)/(0.08265 kg) = 0.394 m ≅ 0.40 m.

d.) % (m/v) of the solution:

∵ (m/v)% = [(mass of solute) /(volume of the solution)]* 100

∴ (m/v)% = [(3.36 g)/(70.5 mL)]* 100 = 4.77%.

e.) % (m/m) of the solution:

∵ (m/m)% = [(mass of solute) /(mass of the solution)]* 100

∴ (m/m)% = [(3.36 g)/(86.01 g)] * 100 = 3.9 %.

4 0

3 years ago