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timofeeve [1]
3 years ago
12

Please help me on this question (4a)

Chemistry
1 answer:
drek231 [11]3 years ago
5 0
You have to draw the arrow going out of the coffee cup and into the environment. Since the coffee is hot, heat will ecscape in order for it to reach room temperature
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A prototype is usually different from the final product
Assoli18 [71]
True. The prototype is usually the "rough draft" the figure out what needs fixed or upgraded before they make the final product "final draft". Hope that helped!
7 0
3 years ago
Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry.
KiRa [710]

Answer:

A) 54.04%

B) 13-karat

Explanation:

A) From the problem we have

<em>1)</em> Mg + Ms = 9.40 g

<em>2)</em> Vg + Vs = 0.675 cm³

Where M stands for mass, V stands for volume, and g and s stand for gold and silver respectively.

We can rewrite the first equation using the density values:

<em>3)</em> Vg * 19.3 g/cm³ + Vs * 10.5 g/cm³ = 9.40

So now we have<em> a system of two equations</em> (2 and 3) <em>with two unknowns</em>:

We <u>express Vg in terms of Vs</u>:

  • Vg + Vs = 0.675 cm³
  • Vg = 0.675 - Vs

We <u>replace the value of Vg in equation 3</u>:

  • Vg * 19.3 + Vs * 10.5 = 9.40
  • (0.675-Vs) * 19.3 + Vs * 10.5 = 9.40
  • 13.0275 - 19.3Vs + 10.5Vs = 9.40
  • -8.8 Vs + 13.0275 = 9.40
  • <u>Vs = 0.412 cm³</u>

Now we <u>calculate Vg</u>:

  • Vg + Vs = 0.675 cm³
  • Vg + 0.412 cm³ = 0.675 cm³
  • Vg = 0.263 cm³

We <u>calculate Mg from Vg</u>:

  • 0.263 cm³ * 19.3 g/cm³ = 5.08 g

We calculate the mass percentage of gold:

  • 5.08 / 9.40 * 100% = 54.04%

B)

We multiply 24 by the percentage fraction:

  • 24 * 54.04/100 = 12.97-karat ≅ 13-karat
4 0
3 years ago
Which substance is most likely to heat up the fastest?
ddd [48]
The best substance to heat up the fastest would be blue fire
7 0
3 years ago
Read 2 more answers
Please help very urgent! &lt;3
LuckyWell [14K]

Answer:

a) Neutralisation

b) Combustion

c) Synthesis

d) Decomposition

e) Neutralisation

f) Double Displacement Reaction

h) Single Displacement Reaction

i) Double Displacement Reaction

j) Combustion

Explanation:

Synthesis  is a reaction where various compounds/ elements react to form a totally new compound.

Decomposition is a reaction where a single compound breaks down into several components due to excessive heating or energy applied.

Single Displacement Reaction is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound.

Double Displacement Reaction is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.

Combustion is a reaction where a compound/ element oxidises in the presence of Oxygen.

Neutralisation reaction is a reaction where an acid reacts with a base to form a salt.

5 0
3 years ago
Twenty students were surveyed to find out how many hours of TV they watch during a school week. The results are shown to the rig
natulia [17]

Answer: 4.5

Explanation:

Just did it

8 0
3 years ago
Read 2 more answers
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