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3 years ago

6

Hydrogen is in Group 1A of the periodic table, known as the alkali metals, although it obviously isn't a metal. What is the reas

on for its placement in this group? A) Hydrogen has the same electron configuration as alkali metals. B) Hydrogen is a metal, but has an extremely low vaporization point. C) There isn't room for hydrogen on the right side of the table with other nonmetals. D) Scientists didn't want to reconfigure the periodic table after they discovered that hydrogen wasn't a metal. 7)

2 answers:

maria [59]3 years ago

7 0

The answer is a because it's electron configuration is ns1

Dominik [7]3 years ago

6 0

Answer:

The answer is A

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1/ Which graph illustrates constant speed and velocity

Maksim231197 [3]

Velocity is said to be constant if its magnitude as well direction at any instant is remains the same. In D, if you draw a line parallel to y-axis at any time t, you can see that velocity is same. Hence, D is the correct graph.

The kinetic energy of gaseous molecules is greater than that of liquid molecules. Therefore, in gas, kinetic energy overcomes the force of attraction between molecules. In short, in gas phase, particles move at high speed and hence they have less force of attraction. In case of liquid phase, particles are close enough as a result there is much more force of attraction compared to gaseous molecules. In liquid state, kinetic energy cannot overcome force of attraction therefore, liquid molecules slow down.

Therefore, B is the correct answer.

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3 years ago

1. Imagine that you need to take a medicine that the doctor has prescribed for you. Explain why scientists who developed that me

ella [17]

Answer: The compound in medicines should be non polar.

It is important for any drug to be able to dissolve itself through the cell membrane which consists of a lipid bi-layer, in order to diffuse in the body and circulate biologically, performing its function.

Non polar compounds are lipid soluble and therefore can dissolve in the lipid layers.

Polar compounds are water soluble and fail to cross the cell membrane.

Therefore scientists need to be sure of using compounds that are non polar in nature so they pass through the cell membrane and enter into the blood circulation of the body and perform its due function.

Explanation:

6 0

3 years ago

When 0.620 gMngMn is combined with enough hydrochloric acid to make 100.0 mLmL of solution in a coffee-cup calorimeter, all of t

OleMash [197]

Answer:

The enthalpy change during the reaction is -199. kJ/mol.

Explanation:

$Mn(s)+2HCl(aq)\rightarrow MnCl_2(aq)+H_2(g)$

Mass of solution = m

Volume of solution = 100.0 mL

Density of solution = d = 1.00 g/mL

$m=1.00 g/mL\times 100.0 mL = 100 g$

First we have to calculate the heat gained by the solution in coffee-cup calorimeter.

$q=m\times c\times (T_{final}-T_{initial})$

where,

m = mass of solution = 100 g

q = heat gained = ?

c = specific heat = $4.18 J/^oC$

$T_{final}$ = final temperature = $23.1^oC$

$T_{initial}$ = initial temperature = $28.9^oC$

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

$q=100 g \times 4.18 J/^oC\times (28.9-23.1)^oC$

$q=2,242.4 J=2.242 kJ$

Now we have to calculate the enthalpy change during the reaction.

$\Delta H=-\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat gained = 2.242 kJ

n = number of moles fructose = $\frac{\text{Mass of manganese}}{\text{Molar mass of manganese}}=\frac{0.620 g}{54.94 g/mol}=0.0113 mol$

$\Delta H=-\frac{2.242 kJ}{0.0113 mol }=-199. kJ/mol$

Therefore, the enthalpy change during the reaction is -199. kJ/mol.

8 0

2 years ago

A calorimeter contains 22.0 mL of water at 14.0 ∘C . When 2.50 g of X (a substance with a molar mass of 82.0 g/mol ) is added, i

Alik [6]

Answer:

The enthalpy change in the the reaction is -47.014 kJ/mol.

Explanation:

$X(s)+H_2O(l)\rightarrow X(aq)$

Volume of water in calorimeter = 22.0 mL

Density of water = 1.00 g/mL

Mass of the water in calorimeter = m

$m=1.00 g/mL\times 22.0 mL=22 g$

Mass of substance X = 2.50 g

Mass of the solution = M = 2.50 g + 22 g = 24.50 g

Heat released during the reaction be Q

Change in temperature =ΔT = 28.0°C - 14.0°C = 14.0°C

Specific heat of the solution is equal to that of water :

c = 4.18J/(g°C)

$Q=Mc\times \Delta T$

$Q=24.50 g\times 4.18 J/g ^oC\times 14.0^oC=1,433.74 J=1.433 kJ$

Heat released during the reaction is equal to the heat absorbed by the water or solution.

Heat released during the reaction =-1.433 kJ

Moles of substance X= $\frac{2.50 g}{82.0 g/mol}=0.03048 mol$

The enthalpy change, ΔH, for this reaction per mole of X:

$\Delta H=\frac{-1.433 kJ}{0.03048 mol}=-47.014 kJ/mol$

5 0

2 years ago

The quantity of energy released or absorbed as heat during a chemical reaction is called the 28. a. temperature. c. entropy d. f

Tatiana [17]

Answer: enthalpy of reaction.

Explanation:

Temperature of the gas is defined as the degree of hotness or coldness of a body. It is expressed in units like $^0C$ and $K$

Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

Free energy is the amount of energy that can be converted into useful work.

Enthalpy of the reaction is the difference between the energy of products and the energy of reactants. it is either the heat released or absorbed during the reaction. It is either positive or negative.

5 0

3 years ago