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4 years ago

Which of the listed properties is the same for the elements beryllium (Be), magnesium (Mg), and calcium (Ca)?

Chemistry

2 answers:

Setler79 [48]4 years ago

7 0

Answer is valence electron, they all have total of 2 valence electron.
remember group number = valence electron

Alex_Xolod [135]4 years ago

7 0

Answer: The correct answer is number of valence electrons.

Explanation:

Elements are distributed into 7 Periods and 18 groups in periodic table.

Elements that belong to same group show similar chemical properties because they have same number of valence electrons.

Beryllium belongs to Group 2 and period 2 of the periodic table.

Magnesium belongs to Group 2 and period 3 of the periodic table.

Calcium belongs to Group 2 and period 4 of the periodic table.

Hence, the correct answer is number of valence electrons.

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A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution

Dmitrij [34]

Answer:

The change in internal energy is - 1.19 kJ

Explanation:

Step 1: Data given

Heat released = 3.5 kJ

Volume calorimeter = 0.200 L

Heat release results in a 7.32 °C

Temperature rise for the next experiment = 2.49 °C

Step 2: Calculate Ccalorimeter

Qcal = ccal * ΔT ⇒ 3.50 kJ = Ccal *7.32 °C

Ccal = 3.50 kJ /7.32 °C = 0.478 kJ/°C

Step 3: Calculate energy released

Qcal = 0.478 kJ/°C *2.49 °C = 1.19 kJ

Step 4: Calculate change in internal energy

ΔU = Q + W W = 0 (no expansion)

Qreac = -Qcal = - 1.19 kJ

ΔU = - 1.19 kJ

The change in internal energy is - 1.19 kJ

4 0

4 years ago

011 10.0 points

Sphinxa [80]

Answer:

$-58.3^{\circ}C$

Explanation:

The frequency and the wavelength of a wave are related by the equation

$v=f\lambda$

where

v is the speed

f is the frequency

$\lambda$ is the wavelength

For the sound wave in this problem, we have

f = 634 Hz (frequency)

$\lambda=0.47 m$ (wavelength)

Therefore, the speed of the wave is

$v=(634)(0.47)=298 m/s$

The speed of sound in air depends on the temperature according to the equation

$v=333+0.6 T$

where T is the temperature.

In this problem, we know the speed, so we can calculate the temperature:

$T=\frac{v-333}{0.6}=\frac{298-333}{0.6}=-58.3^{\circ}C$

7 0

3 years ago

G.com what is the mass of a gold bar that is 7.379 × 10–4 m3 in volume

tiny-mole [99]

7.379 * 10^(-4) is measured, hence prone to error, either human error or via measuring device. In this case,
100 cm = 1 m is written in stone and is unquestionable.
The density of the gold is 19.3 g/cm^3 and could be an approximation.
The approximation is good to at least one night.

5 0

3 years ago

Calcium and what makes bones hard

Ira Lisetskai [31]

Bones are made up of a framework of a protein called collagen , with a mineral called calcium phosphate that makes the framework hard and strong. Bones store calcium and release some into the bloodstream when it's needed by other parts of the body.

5 0

3 years ago

Is the genie in the bottle experiment a physical or chemical change/reaction?

gladu [14]

Answer:

Chemical reaction.

Step-by-step explanation:

In the experiment, a catalyst is added to concentrated hydrogen peroxide.

The hydrogen peroxide decomposes rapidly, according to the equation

2H₂O₂(ℓ) ⟶ 2H₂O(ℓ) + O₂(g)

New substances are formed, and old ones disappear, so this is a chemical reaction.

The reaction also releases a large amount of heat.

The rapidly-expanding oxygen gas caries with it droplets of water and hydrogen peroxide (and probably some steam, as well).

The visual effect is like a genie escaping from its bottle.

4 0

3 years ago