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3 years ago

ASAP MULTIPLE CHOICE

Chemistry

1 answer:

nata0808 [166]3 years ago

8 0

Its J.J Thomson i took the test

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Describe the distribution of mass within an atom

san4es73 [151]

Answer:

The nuclei of most atoms also contain neutrons . The masses of subatomic particles are very tiny. ... Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.

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3 years ago

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A 0.500-g sample of KCl is added to 50.0g of water in a calprimeter (Figure 5.12) If the temperature decreases by 1.05C. what is

Sauron [17]

Answer : The reaction is endothermic.

Explanation :

Formula used :

$Q=m\times c\times \Delta T$

where,

$\Delta T$ = change in temperature = $1.05^oC$

Q = heat involved in the dissolution of KCl = ?

m = mass = 0.500 + 50.0 = 50.5 g

c = specific heat of resulting solution = $4.18J/g^oC$

Now put all the given value in the above formula, we get:

$Q=50.5g\times 4.18J/g^oC\times 1.05^oC$

$Q=+221.64J$

The heat involved in the dissolution of KCl is positive that means as the change in temperature decreases then the reaction is endothermic and as the change in temperature increases then the reaction is exothermic.

Hence, the reaction is endothermic.

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3 years ago

A buffer solution is composed of 4.00 4.00 mol of acid and 3.25 3.25 mol of the conjugate base. If the p K a pKa of the acid is

Reika [66]

Answer: The pH of the buffer is 4.61

Explanation:

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[\text{conjuagate base}]}{[\text{acid}]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of weak acid = 4.70

$[\text{conjuagate base}]}$ = moles of conjugate base = 3.25 moles

$[\text{acid}]$ = Moles of acid = 4.00 moles

pH = ?

Putting values in above equation, we get:

$pH=4.70+\log(\frac{3.25}{4.00})\\\\pH=4.61$

Hence, the pH of the buffer is 4.61

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3 years ago

What evidence would support Maria's claim that the fossilized remains are that of a bird, class Aves, instead of a turtle, class

lora16 [44]

Your answer would be C.

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3 years ago

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What type of compound does the formula, CuCl2, represent? a. ionic salt b. covalent molecule

Rainbow [258]

The answer is: [B]: "ionic salt" .
___________________________________________________
Note: There is no "sharing of electrons" among the elements in this compound; so this compound in NOT a "covalent molecule".

However, there is ionic bonding: Cu²⁺ and Cl⁻ ; to form: "CuCl₂" .
____________________________________________________

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3 years ago