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3 years ago

14

What is the number of electrons in the highest occupied energy level of an element in Group 5A?

1 answer:

nignag [31]3 years ago

8 0

5 is the answer i took the test

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Which of the following does not change when a car keeps a constant speed but changes direction?

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An object which experiences either a change in the magnitude or the direction of the velocity vector can be said to be accelerating. This explains why an object moving in a circle at constant speed can be said to accelerate - the direction of the velocity changes.

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3 years ago

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Elements in a given period of the periodic table contain the same number of

leva [86]

Its C, Outermost Electrons.

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2 years ago

4. In the chemical equation H202(aq) → H2O(l) + O2(g), the O2 is a

Gala2k [10]

Answer:

02 is a product

Explanation:

it doesnt take part in chemical reaction so its not reactant.02 doesnt alter rate of chemical reaction so it cannot be catalyst. it is gas it is not solid so it is a product.

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3 years ago

What is the half life of a compound if 75% of a given sampleof

Contact [7]

Answer:

$t_{1/2}=30.14\ min$

Explanation:

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Given:

75 % is decomposed which means that 0.75 of $[A_0]$ is decomposed. So,

$\frac {[A_t]}{[A_0]}$ = 1 - 0.75 = 0.25

t = 60 min

$\frac {[A_t]}{[A_0]}=e^{-k\times t}$

$0.25=e^{-k\times 60}$

k = 0.023 min⁻¹

Considering the expression for half life as:-

$t_{1/2}=\frac {ln\ 2}{k}$

Where, k is rate constant

So,

$t_{1/2}=\frac{\ln 2}{0.023}\ min$

$t_{1/2}=30.14\ min$

5 0

2 years ago

An electrical heater is used to add 21.75 kJ of heat to aconstant-volume calorimeter. The temperature of the calorimeterincrease

AlexFokin [52]

Answer:

The molar heat of combustion for butanol is 2.7 *10³ kJ/mol

Explanation:

Step 1: Data given

Temperature change = 4.18 °C

mass of butanol = 3.00 grams

When butanol is burned Temperature change = 20.81 °C

Step 2: Calculate Ccalorimeter

Ccal = 21750J / 4.18 °C = 5203.35 J/ °C

Step 3: Calculate heat generated

Heat generated = 20.81 °C * 5203.35 J/°C = 108281.71 J = 108.28 kJ

Step 4: Calculate moles of butanol

Number of moles = mass / molar mass

Number of moles = 3 grams / 74.123 g/mol = 0.04 moles

Step 5: Calculate Molar heat of combustion

Molar heat of combustion = 108.28 kJ / 0.04 moles = 2707 kJ /mol

The molar heat of combustion for butanol is 2.7 *10³ kJ/mol

3 0

2 years ago