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stepan [7]
3 years ago
11

What can scientists learn from index fossils?

Chemistry
1 answer:
olga2289 [7]3 years ago
3 0

Answer:

dating and correlating the strata in which it is found

Explanation:

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Where do producers get matter and energy to live and grow ?
bixtya [17]

Answer:c

Explanation:

8 0
3 years ago
The coordination number of cation and anion in fluorite CaF2 and antifluorite Na2O are respectively​
sp2606 [1]

<u>8:4 and 4:8</u> both have CCP structure............................... ᐛ

6 0
3 years ago
Protein x has an absorptivity of 0.4 ml·mg-1 ·cm-1 at 280 nm. What is the absorbance at 280 nm of a 2.0 mg ·ml-1 solution of pro
Evgen [1.6K]

Absorbance measures the ability of the substance to absorb light at a specific wavelength.

Absorbance is also equal to the product of molar absorptivity, path length and molar concentration.

The mathematical expression is given as:

A= \epsilon l c       (1)

where, A = absorbance

\epsilon =  molar absorptivity

l = path length

c  = molar concentration.

The above formula is said to Beer's Law.

Absorptivity of protein x  = 0.4 mLmg^{-1}cm^{-1}

Path length = 1 cm

Molar concentration = 2.0 mg mL^{-1}

Put the values in formula (1)

Absorbance at 280 nm = 0.4 mL mg^{-1}cm^{-1}\times 1 cm \times 2.0 mg mL^{-1}

= 0.8

Thus, absorbance at 280 nm = 0.8

3 0
3 years ago
Which of these gives a correct trend in ionization energy​
natita [175]

Answer:

C. I, III , IV

Explanation:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also  decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

3 0
3 years ago
How can the rate of a reaction be increased?
Nana76 [90]
I think it may be A.
But I'm not sure






4 0
3 years ago
Read 2 more answers
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