I need help with #22

What would be the volume in millilitres of a blood sample of 2.15 microliters (ul)?

Zanzabum

2.15 x 10⁻³mL

Explanation:

Given parameter:

Volume of blood sample in uL = 2.15uL

Conversion uL → mL

micro- and milli- are both prefixes of sub-units.

liter is a unit of volume of a substance.

micro - is 10⁻⁶

milli- is of the order 10⁻³

The problem is converting from micro to milli:

if we multiply 10⁻⁶ by 10³ we would have our milli;

1000uL = 1mL

2.15uL : 2.15uL x $\frac{1mL}{1000uL}$ = 2.15 x 10⁻³mL

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4 0

3 years ago

The reaction of iron with oxygen to form iron oxide is an example of an oxidation–reduction reaction: 4fe + 3o2 → 2fe2o3. in thi

nadya68 [22]

Answer:-

Oxygen gains electrons and is reduced.

Explanation:-

For this reaction the balanced chemical equation is

4Fe + 3O2 --> 2Fe2O3

When Oxygen is present as oxygen gas, the oxidation number of O is Zero since it is the only element present in Oxygen gas.

Similarly Iron is present in Fe with oxidation number Zero.

In the case of Fe2O3, Oxygen has the oxidation number -2 while Iron has +3.

So the oxidation number of Oxygen goes from Zero to -2.

Since the oxidation number decreases Oxygen is reduced.

Since reduction involves gain of electrons, Oxygen gains electrons.

4 0

3 years ago

Different kinds of wood have different densities. The density of american white oak wood is generally 0.77 g/cm3. If Jim grabs a

mixas84 [53]

Answer:

m= 29.645 g

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

density of wood = 0.77 g/cm³

volume= 38.5 cm³

mass= ?

Solution:

d= m/v

m= d × v

m= 0.77 g/cm³× 38.5 cm³

m= 29.645 g

7 0

3 years ago

Select the correct answer. Based on the reactivities of the elements involved, which reaction will form products that are more s

FinnZ [79.3K]

Answer: The correct answer is option B.

Explanation: Reactivity of elements is defined as the tendency to loose or gain electrons.

These reactions are a type of single displacement reactions. A single displacement reaction is a type of reaction in which an element displaces another element in a chemical reaction. These are studied with the help of reactivity series.

The element which lies above in the reactivity series can easily displace the element which lies below in the reactivity series.

Option A: This reaction will not yield a stable product because Zinc lies below Aluminium in the reactivity series.

$AlBr_3+Zn\rightarrow \text{No reaction}$

Option B: This reaction will yield a stable product because Sodium lies above Calcium in the reactivity series.

$CaBr_2+2Na\rightarrow 2NaBr+Ca$

Option C: This reaction will not yield a stable product because Hydrogen lies below Magnesium in the reactivity series.

$MgBr_2+H_2\rightarrow \text{No reaction}$

Option D: This reaction will not yield a stable product because Calcium lies below Barium in the reactivity series.

$BaBr_2+Ca\rightarrow \text{No reaction}$

Option E: This reaction will not yield a stable product because barium lies below Lithium in the reactivity series.

$2LiBr+Ba\rightarrow \text{No reaction}$

8 0

3 years ago

Which of the following combinations will result in a reaction that is spontaneous at all temperatures?

Katen [24]

Answer:

$\huge\boxed{Option \ 2}$

Explanation:

A reaction is spontaneous at all temperatures by the following combinations:

=> A negative enthalpy change ( $\triangle H < 0$ )

=> A positive entropy change ( $\triangle S > 0$ )

See the attached file for more better understanding!

8 0

3 years ago

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