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USPshnik [31]
2 years ago
7

Assertion (A): Naphthalene balls disappear with time without leaving any solid.

Chemistry
2 answers:
gogolik [260]2 years ago
7 0

Explanation:

a) Both A and R are true and R is the correct

explanation of A.

Kruka [31]2 years ago
7 0

Answer:

\fbox {c) A is true but R is false.}

Explanation:

Assertion (A):

⇒ Naphthalene balls disappear with time without leaving any solid.

⇒ True √

Reason (R):

⇒ Solid converted to liquid is called sublimation.

⇒ False ×

⇒ Solid converted to liquid is called <u>melting</u>

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When 2.50 g of an unknown weak acid (ha) with a molar mass of 85.0 g/mol is dissolved in 250.0 g of water, the freezing point of
baherus [9]
When dT = Kf * molality * i
                = Kf*m*i
and when molality = (no of moles of solute) / Kg of solvent
                               = 2.5g /250g x 1 mol /85 g x1000g/kg
                               =0.1176 molal
and Kf for water = - 1.86 and dT = -0.255
by substitution 
0.255 = 1.86* 0.1176 * i
∴ i = 1.166
when the degree of dissociation formula is: when n=2 and  i = 1.166
a= i-1/n-1 = (1.166-1)/(2-1) = 0.359 by substitution by a and c(molality) in K formula
∴K = Ca^2/(1-a)
     = (0.1176 * 0.359)^2 / (1-0.359)
     = 2.8x10^-3



5 0
3 years ago
Rewrite each equation below with the delta H value included with either the reactants or the products and identify the reaction
yanalaym [24]
A) 2H₂(g) + O₂(g) → 2H₂O(l) + 285.83 kJ
Exothermic

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5 0
3 years ago
A rigid tank contains 0.66 mol of oxygen (O2). Find the mass of oxygen that must be withdrawn from the tank to lower the pressur
dsp73

Answer:

12.8 g of O_{2} must be withdrawn from tank

Explanation:

Let's assume O_{2} gas inside tank behaves ideally.

According to ideal gas equation- PV=nRT

where P is pressure of O_{2}, V is volume of O_{2}, n is number of moles of O_{2}, R is gas constant and T is temperature in kelvin scale.

We can also write, \frac{V}{RT}=\frac{n}{P}

Here V, T and R are constants.

So, \frac{n}{P} ratio will also be constant before and after removal of O_{2} from tank

Hence, \frac{n_{before}}{P_{before}}=\frac{n_{after}}{P_{after}}

Here, \frac{n_{before}}{P_{before}}=\frac{0.66mol}{43atm} and P_{after}=17atm

So, n_{after}=\frac{n_{before}}{P_{before}}\times P_{after}=\frac{0.66mol}{43atm}\times 17atm=0.26mol

So, moles of O_{2} must be withdrawn = (0.66 - 0.26) mol = 0.40 mol

Molar mass of O_{2} = 32 g/mol

So, mass of O_{2} must be withdrawn = (32\times 0.40)g=12.8g

7 0
3 years ago
What are the Characteristics of handwriting?
mel-nik [20]

Answer:

the specific shape of letters, e.g. their roundness or sharpness.

regular or irregular spacing between letters.

the slope of the letters.

the rhythmic repetition of the elements or arrhythmia.

the pressure to the paper.

the average size of letters.

the thickness of letters.

5 0
3 years ago
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If a substance changes from one phase to another, is it still same substance? why
shutvik [7]
When you boil water, you aren't changing the elements. You're just making water vapor. However, when you burn paper, it becomes carbon (mostly). So physical changes will not change the substance, only chemical changes will.
5 0
3 years ago
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