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3 years ago

What are the structural features of purines and pyrimidines?

1 answer:

7 0

The purines in DNA are adenine and guanine, the same as in RNA. The pyrimidines in DNA are cytosine and thymine; in RNA, they are cytosine and uracil. Purines are larger than pyrimidines because they have a two-ring structure while pyrimidines only have a single ring

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Answer the question - How many moles

77julia77 [94]

Answer:

PRACTICE MULTIPLE CHOICE QUESTIONS FROM UNIT 10

1.) A cylinder is filled with 2.00 moles of nitrogen, 3.00 moles of argon, and 5.00 moles of helium. If

the gas mixture is at STP, what is the partial pressure of the argon?

(A) 152 torr (B) 228 torr (C) 380. torr (D) 760. torr

2.) Compared to the average kinetic energy of 1 mole of water at 0 oC, the average kinetic energy

of 1 mole of water at 298 K is

(A) the same, and the number of molecules is the same

(B) the same, but the number of molecules is greater

(D) greater, but the number of molecules is the same

3.) If the pressure on a given mass of gas in a closed system is increased and the temperature

remains constant, the volume of the gas will

(A) decrease (B) increase (C) remain the same

4.) Which gas has approximately the same density as C2H6 at STP?

(A) NO (B) NH3 (C) H2S (D) SO2

5.) At a temperature of 273 K, a 400. milliliter gas

8 0

3 years ago

What does heat and pressure have to do with the rock cycle?

UkoKoshka [18]

Answer

Metamorphic rocks form from heat and pressure changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock. The word "metamorphic" comes from Greek and means "To Change Form". ... This changing of rock types is called the "Rock Cycle".

Explanation:

4 0

3 years ago

Calculate ΔH∘f for CaC2(s): CaC2(s)+2H2O(l)→Ca(OH)2(s)+C2H2(g) ΔH∘=−127.2kJ

puteri [66]

Below are I think the data for this problem:

Given the following data:

Ca (s) + 2 C (graphite) → CaC2 (s) ∆H = -62.8 kJ 
Ca (s) + ½ O¬2 (g) → CaO (s) ∆H = -635.5 kJ 
CaO (s) + H2O (l) → Ca(OH)2 (aq) ∆H = -653.1 kJ 
C2H2 (g) + 5/2 O¬2 (g) → 2 CO2 (g) + H2O (l) ∆H = -1300 kJ 
C (graphite) + O¬2 (g) → CO2 (g) ∆H = -393.51 kJ

Below is the answer:

CaC2 (s) + 2 H2O (l) → Ca(OH)2 (aq) + C2H2 (g)
So what you do is: 
Times the first equation by -1 Second by 1 Third By 1 Fourth by -1 and Fifth by 2 
So This gives us: 
1.CaC2--> Ca+2C 
2.Ca+1/2O2-->CaO 
3.CaO+H2O-->Ca(OH)2 
4.2CO2+H2O-->C2H2+5/2O2 
5.2C+202-->2CO2 
Now you cancel out like terms on either sides of the equation and you end up with 
CaC2 (s) + 2 H2O (l) → Ca(OH)2 (aq) + C2H2 (g) Just what you wanted 
So to calculate ∆H: 
62.8-635.5-653.1+1300-787.02= -712.82

7 0

4 years ago

Estradiol is a female sexual hormone that causes maturation and maintenance of the female reproductive system. Elemental analysi

Harlamova29_29 [7]

Answer:

The answer to your question is: Molecular formula = C₁₈H₂₄O₂

Explanation:

Estradiol

C = 79.37 %

H = 8.88 %

O = 11.75 %

Molar mass = 272.37

Process

Carbon = 79.37 g

Hydrogen = 8.88 g

Oxygen = 11.75 g

12 g of Carbon ----------------- 1 mol

79.37 g ---------------- x

x = (79.37 x 1) / 12

x = 6.61 mol

1 g of Hydrogen ---------------- 1 mol

8.88 g ---------------- x

x = (8.88 x 1 ) / 1

x = 8.88 mol

16 g of Oxygen ------------------ 1 mol

11.75 g ----------------- x

x = (11.75 x 1) / 16

x = 0.73

Divide by the lowest number of moles

Carbon = 6.61 / 0.72 = 9.2

Hydrogen = 8.88 / 0.73 = 12.2

Oxygen = 0.73/0.73 = 1

Empirical formula

C₉H₁₂O₁

MW of the empirical formula = (12 x 9) + (12 x 1) + (16 x 1)

= 136 g

Divide molar mass of estradiol by the molar mass of the empirical formula.

= 272 / 136

= 2

Then the molecular formula is:

2(C₉H₁₂O) = C₁₈H₂₄O₂

7 0

4 years ago

Which chemical is a reactant in the reaction shown? A. HCI B. CO₂ C. H₂O D. NaCI

zzz [600]

More detail please :)

3 0

4 years ago

Read 2 more answers