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2 years ago

What sea animals have moveable spines that they use for protection

Chemistry

1 answer:

Keith_Richards [23]2 years ago

7 0

Answer:

sea urchins

Explanation:

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Filtration, or screening, is one way to separate certain mixtures, as shown in the image. Which of these mixtures could be most

erastovalidia [21]

Answer: D

Explanation:

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3 years ago

What is the world's biggest material lab?

arlik [135]

M C C O R M I C K T E A M ’ S O P E N Q U A N T U M M AT E R I A L S D ATA B A S E O F F E R S U N L I M I T E D A C C E S S T O ANALYSES OF NEARLY 300,000 COMPOUNDS

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3 years ago

Density is the ratio of a sample's mass to its volume. A bar of lead has a mass of 115.2 g. When it is submerged in 25.0 mL of w

Margarita [4]

Answer:

$10.97 \ g/cm^3$

Explanation:

Given :

Mass of a bar of lead = 115.2 g

Initial water level $\text{in the graduated cylinder}$ = 25 mL

Final water level $\text{in the graduated cylinder}$ = 35.5 mL

Difference in the water level = 35.5 - 25

= 10.5 mL

= $10.5 \ cm^3$

We know that when a body is submerged in water, it displaces its own volume of water.

Therefore, the volume of the lead bar = volume of the water displaced = 10.5 mL = $10.5 \ cm^3$

We know that mathematically, density is the ratio of mass of body to its volume.

Density of the lead bar is given by :

$\rho =\frac{\text{mass}}{\text{volume}}$

$\rho =\frac{\text{115.2 g}}{\text{10.5 cm}^3}$

= $10.97 \ g/cm^3$

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3 years ago

What is the name of the compound with the formula NaHCO3 ?

Marianna [84]

Answer:

Sodium bicarbonate

Explanation:

Sodium bicarbonate ( NaHCO₃ ) -

Sodium bicarbonate , according to the IUPAC nomenclature , its name is sodium hydrogen carbonate ,and in common terms also refereed to as baking soda .

It is a white crystalline solid , it is basic in nature .

The cation and anion of this salt are the sodium ion ( Na⁺) and the anion bicarbonate anion (HCO³⁻) .

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3 years ago

2.Which of the alcohols listed below would you expect to react most rapidly with PBr3?A)CH3CH2CH2CH2CH2CH2OHB)(CH3CH2)2CH(OH)CH2

Gnoma [55]

Answer:

A) CH3CH2CH2CH2CH2CH2OH

Explanation:

For this question, we have the following answer options:

A) CH3CH2CH2CH2CH2CH2OH

B) (CH3CH2)2CH(OH)CH2CH3

C) (CH3CH2)2CHOHCH3

D) (CH3CH2)3COH

E) (CH3CH2)2C(CH3)OH

We have to remember the reaction mechanism of the substitution reaction with $PBr_3$ . The idea is to generate a better leaving group in order to add a "Br" atom.

The $PBr_3$ attacks the "OH" generation new a bond to P (O-P bonds are very strong), due to this new bond we will have a better leaving group that can remove the oxygen an allow the attack of the Br atom to generating a new C-Br bond. This is made by an Sn2 reaction. Therefore we will have a faster reaction with primary substrates. In this case, the only primary substrate is molecule A. So, "CH3CH2CH2CH2CH2CH2OH" will react faster.

See figure 1

I hope it helps!

7 0

3 years ago