Hook was the first to discover cells in a cork. true or false?

Answers

Answer 1

Answer: True, Robert Hooke was the first person to discover cells inside a cork.

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Before arc welding was developed, a displacement reaction involving aluminum and iron(III) oxide was commonly used to produce molten iron (the thermite process). This reaction was used, for example, to connect sections of iron railroad track. Calculate the mass of molten iron produced when 2.28 kg of aluminum reacts with 17.2 mol of iron(III) oxide.
Which of the following is the smallest volume? A. 2500 mL B. 250 cm3 C. 2.5 x 10-2 L D. 25 m3
Andy is waiting at the signal. As soon as the light turns green, he accelerates his car at a uniform rate of 8.00 meters/second2. What is the displacement of Andy’s car after 30.0 seconds?A. 1200 meters B. 2400 meters C. 3600 meters D. 4800 meters E. 7200 meters

According to Bohr's model of the hydrogen atom, what determines the energy of an electron?A. the radius of its orbit
B. the direction of its orbit
C. the stability of its orbit

Answers

Option a: the radius of its orbit.

A car on a 25-m2 hydraulic lift platform weighs 15,000 N. If the force on the smaller piston required to lift it is 1/100 its weight, what is the area of the smaller piston?

Answers

Answer:

The area is 2.5 m²

Explanation:

Step 1: Data given

A car has a 25 m² hydraulic lift platform that weighs 15000 N

The smaller piston required a force to lift = 1/100 its weight

Step 2: Calculate the area of the smaller piston

Pressure = Force / Area

F1 / A1 = F2 / A2

⇒ with F1 = weight of the hydraulic lift = 15000 N

⇒ with A1 = area of the hydraulic lift = 25 m²

⇒ with F2 = 1/100 of it's weight = 1500 N

A2 = F2 / (F1/A1)

A2 = 1500 ( 1500/25)

A2 = 2.5

The area is 2.5 m²

Use electron transfer or electron shift to identify what is oxidized and what is reduced in each reaction :a) 2Na(s) + Br2(l) ----> 2NaBr(s)
b) H2(g) + Cl2(g) ----> 2HCl(g)
c) 2Li(s) + F2(g) ----> 2LiF(s)
d) S(s) + Cl2(g) ----> SCl2(g)
e)N2(g) + 2O2(g) ----> 2NO2(g)
f) Mg(s) +Cu(NO3)2(aq) = Mg(NO3)2(aq) + Cu(s)

For each reaction above, identify the reducing agent and the oxidizing agent

Answers

Answer :

Oxidation-reduction reaction : It is a type of reaction in which oxidation and reduction reaction occur simultaneously.

Oxidation reaction : It is the reaction in which a substance looses its electrons. In the oxidation reaction, the oxidation state of an element increases.

Reduction reaction : It is the reaction in which a substance gains electrons. In the reduction reaction, the oxidation state of an element decreases.

(a) The balanced chemical reactions is,

$2Na(s)+Br_2(l)\rightarrow 2NaBr(s)$

Half reactions of oxidation and reduction are :

Oxidation : $Na\rightarrow Na^(1+)+1e^-$

Reduction : $Br_2+2e^-\rightarrow 2Br^(1-)$

From this we conclude that, 'Na' is oxidized and $'Br_2'$ is reduced in this reaction. The reducing agent is, 'Na' and oxidizing agent is, $'Br_2'$ .

(b) The balanced chemical reactions is,

$H_2(g)+Cl_2(g)\rightarrow 2HCl(g)$

Half reactions of oxidation and reduction are :

Oxidation : $H_2\rightarrow H^(1+)+1e^-$

Reduction : $Cl_2+2e^-\rightarrow 2Cl^(1-)$

From this we conclude that, $'H_2'$ is oxidized and $'Cl_2'$ is reduced in this reaction. The reducing agent is, $'H_2'$ and oxidizing agent is, $'Cl_2'$ .

(c) The balanced chemical reactions is,

$2Li(s)+F_2(g)\rightarrow 2LiF(s)$

Half reactions of oxidation and reduction are :

Oxidation : $Li\rightarrow Li^(1+)+1e^-$

Reduction : $F_2+2e^-\rightarrow 2F^(1-)$

From this we conclude that, 'Li' is oxidized and $'F_2'$ is reduced in this reaction. The reducing agent is, 'Li' and oxidizing agent is, $'F_2'$ .

(d) The balanced chemical reactions is,

$S(s)+Cl_2(g)\rightarrow SCl_2(g)$

Half reactions of oxidation and reduction are :

Oxidation : $S\rightarrow S^(2+)+2e^-$

Reduction : $Cl_2+2e^-\rightarrow 2Cl^(1-)$

From this we conclude that, 'S' is oxidized and $'Cl_2'$ is reduced in this reaction. The reducing agent is, 'S' and oxidizing agent is, $'Cl_2'$ .

(e) The balanced chemical reactions is,

$N_2(g)+2O_2(g)\rightarrow 2NO_2(g)$

Half reactions of oxidation and reduction are :

Oxidation : $N_2\rightarrow N^(4+)+4e^-$

Reduction : $O_2+4e^-\rightarrow 2O^(2-)$

From this we conclude that, $'N_2'$ is oxidized and $'O_2'$ is reduced in this reaction. The reducing agent is, $'N_2'$ and oxidizing agent is, $'O_2'$ .

(f) The balanced chemical reactions is,

$Mg(s)+Cu(NO_3)_2(aq)\rightarrow Mg(NO_3)_2(aq)+Cu(s)$

Half reactions of oxidation and reduction are :

Oxidation : $Mg\rightarrow Mg^(2+)+2e^-$

Reduction : $Cu^(2+)+2e^-\rightarrow Cu$

From this we conclude that, $'Mg'$ is oxidized and $'Cu'$ is reduced in this reaction. The reducing agent is, 'Mg' and oxidizing agent is, 'Cu'.

a) Na is oxidised Br is reduced
b) H is oxidised Cl is reduced
c) Li is oxidised F is reduced
d)S is oxidised Cl is reduced
e) N is oxidised O is reduced
f) Mg is oxidised and N is reduced

Remember: Oxidation= loss and Reduction= gains

Prehistory can be described as _____.what happened last year
what happened millions of years ago
the time prior to the use of written records

Answers

The way we usually think of history is the time of written records; or similar records(auditory, video) when we have direct evidence of what happened as opposed to reconstructing it from archaeological evidence. Pre-history is the time before this: the time prior to the use of written records

Hello,How can you tell if a molecular ion will have one or ore unpaired eletrons?

For example,
"Which of the following molecules is expected to have one or more unpaired electrons? Check all that apply.

O2-
F2+
N22-
O22-"
Any help would be appreciated. ...?

Answers

I believe the correct answers from the choices listed above are the first two options. The molecules O2- and F2+ are expected to have one unpaired electron. This can be determined by looking at the value of the charge. Hope this answers the question.

Final answer:

To determine unpaired electrons, look at the valence electrons in an ion's molecule, accounting for extra or absent electrons due to the ion's charge. For instance, O2- and F2+ have one unpaired electron, but N22- is not a valid ion, and O22- electrons are all paired.

Explanation:

To determine if a molecular ion will have one or more unpaired electrons, we need to look at the number of valence electrons in the molecule and take into account any extra or absent electrons due to the charge of the ion.

For example, O2- has 12 + 1 = 13 valence electrons (6 from each oxygen atom and 1 extra due to the negative charge). It requires 14 for all the electrons to be paired (2 in each oxygen's inner shell and 4 bonds or lone pairs in the outer shell), thus there is one unpaired electron in O2-.

However, in F2+, there are only 13 electrons because one electron is lost due to the positive charge. Like oxygen, fluorine also prefers to have 7 electrons in its outer shell, so there are also unpaired electrons in F2+.

N22- doesn’t exist because nitrogen normally forms triple bond and doesn’t need or want to take extra electrons, so this molecular ion is not valid.

O22- has 14 + 2 = 16 valence electrons and this total number of valence electrons is an even number, which indicates all the electrons are paired.

Learn more about Unpaired Electrons here:

brainly.com/question/29656941

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Cohesion is the tendency for the same type of molecules to stick together. TRUE or FALSE

Answers

true

cohesion is the tendency for the same type of molecules to stick together!

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