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Anika [276]
3 years ago
10

Who was the first person to discover the existence of electrons​

Chemistry
2 answers:
nignag [31]3 years ago
6 0

Answer:

JJ Thomson was the first person to discover the existence of electrons. Although Julius plucker in 1859 observed electrons he couldn't specify his observations instead Thomson was the one who further studied plucker observations and specified it as electrons..

k0ka [10]3 years ago
4 0
Electron was discovered by J. J. Thomson in 1897 when he was studying the properties of cathode ray.
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When 100ml of M HCl is mixed with 100ml of N NaOH, the pH of the resulting solution is
RoseWind [281]

Answer:

Option d. 7

Explanation:

A mixture of a strong base and a strong acid produce a neutral salt and water.

This is the reaction of neutralization:

HCl + NaOH → NaCl + H₂O

NaCl →  Na⁺  +  Cl⁻

Sodium chloride is neutral salt which does not give H⁻ neither OH⁻ to medium, that's why pH is neutral.

Both ions are derivated from a strong acid and base so they do not make hydrolisis. They are a conjugate pair of a weak acid and base. The reactions can not occur:

Cl⁻  +  H₂O ← OH⁻  +  HCl

Na⁺  +  H₃O⁺ ← NaOH  + H₂O

4 0
3 years ago
The recommended maintenance dose of penicillin for children is 1.0 mg/kg/hr by injection. Of 10 mL of a 25 mg/mL solution of pen
SOVA2 [1]

This problem is providing us with the recommended maintenance dose of penicillin for children as 1.0 mg/kg/hr by injection. Thus, the delivery rate for a 40-pound child is required, if 10 mL of a 25 mg/mL solution of penicillin is added to a 100-mL bottle of saline. At the end, the result is 8.0 mL/hr:

<h3>Dimensional analysis:</h3>

In chemistry, dimensional analysis allows us to obtain a specific result given relevant information about it. Although a formula is not always provided, one can use the units as a reference for the calculations.

For example, this problem asks for the rate, in mL/hr, at which a child gets this dose, so the first step will be to get the mass of the child in kilograms:

40 lb*\frac{0.4536kg}{1lb}= 18.144kg

Next, we calculate the rate at which the penicillin is delivered to this child:

1.0\frac{mg}{kg*hr} *18.144kg=18.144\frac{mg}{hr}

After that, we calculate the total mass of penicillin that is delivered:

10mL*25\frac{mg}{mL} =250 mg

And get the new concentration once it is diluted to 100 mL:

\frac{250mg}{10mL+100mL}=2.27\frac{mg}{mL}

And finally, we combine the mg/hr with the mg/mL to get the result in mL/hr as required:

18.144\frac{mg}{hr} *\frac{1mL}{2.27mg}\\ \\=8.0\frac{mL}{hr}

Learn more about dimensional analysis: brainly.com/question/10874167

5 0
2 years ago
Explain how creativity can play a role in the construction of scientific questions and hypotheses.
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Like if you imagine making something you create a hypothesis about was to make that happen
6 0
3 years ago
Which statement describes the result of this type of reproduction?
Aleksandr-060686 [28]
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6 0
2 years ago
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A 1.59 mol sample of Kr has a volume of 641 mL. How many moles of Kr are in a 4.41 L sample at the same temperature and pressure
Marina86 [1]

Answer:

The correct answer is 10.939 mol ≅ 10.94 mol

Explanation:

According to Avogadro's gases law, the number of moles of an ideal gas (n) at constant pressure and temperature, is directly proportional to the volume (V).

For the initial gas (1), we have:

n₁= 1.59 mol

V₁= 641 mL= 0.641 L

For the final gas (2), we have:

V₂: 4.41 L

The relation between 1 and 2 is given by:

n₁/V₁ = n₂/V₂

We calculate n₂ as follows:

n₂= (n₁/V₁) x V₂ = (1.59 mol/0.641 L) x 4.41 L = 10.939 mol ≅ 10.94 mol

5 0
2 years ago
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