Answer:
It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays
Which is a component of John Dalton’s atomic theory?
The ratio of atoms in a compound is fixed.
The atoms of different elements are the same.
An atom is a small particle of matter that can be broken down.
A reaction can create or destroy atoms as well as rearrange them.
Answer:
i think the answer is b
Explanation:
Based on periodic trends which atom has a larger ionization energy then calcium Ca?
Answer:
Gallium, Germanium, Arsenic, Selenium, Bromine and Krypton
Explanation:
Based on periodic trends, the atom that has a larger ionization energy than calcium are Gallium, Germanium, Arsenic, Selenium, Bromine and Krypton.
Across the period, the ionization energy increases from left to right.
Ionization energy is the energy required to remove the most loosely held electron within an atom. As you go from left to right, the ionization energy increases rapidly.The elements to the right of Ca will have a higher ionization energy compared to Ca.A 25 cm sample of dilute sulfuric acid contains 0.025 moles of the acid.
What is the hydrogen ion concentration in the solution?
A. 0.2 mol/dm3
B. 0.05 mol/dm3
C. 1.00 mol/dm3
D. 2.00 mol/dm3
Answer:B. 0.05 mol/dm3
Explanation:
The hydrogen ion concentration in the solution is 2 mol/dm³
The correct answer to the question is Option D. 2 mol/dm³
We'll begin by calculating the molarity of the solution.
Volume = 25 cm³ = 25 / 1000 = 0.025 dm3
Mole of H₂SO₄ = 0.025 mol
Molarity of H₂SO₄ =?Molarity = mole / Volume
Molarity of H₂SO₄ = 0.025 / 0.025
Molarity of H₂SO₄ = 1 mol/dm³Finally, we shall determine the concentration of Hydrogen ion in the solution.H₂SO₄(aq) —> 2H⁺(aq) + SO₄²¯(aq)
From the balanced equation above,
1 mole of H₂SO₄ contains 2 moles of H⁺.
Therefore,
1 mol/dm³ H₂SO₄ will also contain 2 mol/dm³ H⁺.
Thus, the concentration of Hydrogen ion in the solution is 2 mol/dm³
The correct answer to the question is Option D. 2 mol/dm³
Learn more: https://brainly.com/question/3655413
What pH scale number represents a neutral.
What pH scale number represents a neutral.
The answer is 7
which formula represents a nonpolar molecule containing polar covelant bond
Answer: H2O and NH3 are polar molecules. H2 is a nonpolar molecule but the H-H bond is also nonpolar.
Therefore, the best choice is CCl4. Although the C-Cl bond is polar due to electronegativity differences, the molecule itself is nonpolar because the net dipole moments cancel out, given its tetrahedral molecular structure.
Explanation:
A current of 5.29 A is passed through a Sn(NO3)2 solution for 1.30 h . How much tin is plated out of the solution?
Answer:
15.26 g of tin
Explanation:
Given that the equation of the process is;
Sn^2+(aq) + 2e ------> Sn(s)
Since 1e = 1F= 96500 C
but q =It
t is in hours so it must be converted to seconds, the SI unit of time
Hence;
119g of tin is deposited by 2 * 96500 C
xg of tin is deposited by 5.29 * 1.30 * 60 * 60
x = 119 * 5.29 * 1.30 * 60 * 60/ 2 * 96500
x = 2946106.8/193000
x= 15.26 g of tin
A current of 5.29 A is passed through a Sn(NO₃)₂ solution for 1.30 hour, the amount of tin plated is 15.26 grams.
How do we calculate mass?Mass of any deposited susbatnce that is obtained by the passing of current will be calculated by using the Faraday's Law as:
W = ECT/F, where
W = required mass of deposited tin
C = current = 5.29 A
T = time period = 1.30hr = 4,680sec
F = faradays constant = 96500C
E = equivalent mass
Equivalent mass will be calculated as:
E = molar mass/charge on atom = 119/2 = 59.5 g/equ
On putting all these values in the above equation, we get
W = (59.5)(5.29)(4680) / 96500
W = 15.26 g
Hence mass of tin is 15.26 g.
To know more about Faraday's Law, visit the below link:
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When [H+] = 4.0 × 10–9 M in water at 25°C, then
Kw =1.0×10–14.
b. pOH = 7.
c. [H3O+] = [OH–].
d. pH= 7
e. A-D are all correct
Answer:
a. Kw = 1.0 × 10⁻¹⁴
Explanation:
a. Let's consider the self-ionization of water.
2 H₂O(l) ⇄ H₃O⁺(aq) + OH⁻
The ion-product of water (Kw) at 25 °C is:
Kw = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴
c. Considering [H⁺] = [H₃O⁺] = 4.0 × 10⁻⁹ M, the concentration of OH⁻ is:
[OH⁻] = 1.0 × 10⁻¹⁴/[H₃O⁺] = 2.5 × 10⁻⁶ M
b. We can calculate the pOH using the following expression.
pOH = -log [OH⁻] = -log 2.5 × 10⁻⁶ = 5.6
d. We can calculate the pH using the following expression.
pH = -log [H⁺] = -log 4.0 × 10⁻⁹ = 8.4
When [H+] = 4.0 × 10–9 M in water at 25°C, then the [tex]Kw =1.0\times 10^-^1^4.[/tex]
What is dissociation constant?
Kw is the dissociation constant or ionization constant of water.
The self-ionization of water will be
[tex]\rm 2 H_2O(l) = H_3O^+(aq) + OH^-[/tex]
The dissociation constant of the water at 25°C will be
[tex]\rm Kw = [H_3O^+][OH^-] = 1.0 \times 10^-^1^4[/tex]
Thus, the correct option is a. [tex]Kw =1.0\times 10^-^1^4.[/tex]
Learn more about dissociation constant
https://brainly.com/question/3657057
what are 4 sources of electrical energy?
Answer:
Clean Energy. Learn more about energy from solar, wind, water, geothermal, biomass and nuclear. Fossil. Learn more about our fossil energy sources: coal, oil and natural gas.Electric Power. Learn more about how we use electricity as an energy source. Energy Storage. Hydrogen & Fuel Cells.Explanation:
I hope this helps xD
Answer:
Electrical energy is used to power up a light bulb. The current moves from the outlet to the light bulb through the wire.
Lightning is another example of electrical energy. The negatively charged particles are separated from the positively...
Batteries are also sources of electrical energy. In car batteries, the moving charges Explanation:
fI gave u 3 think of the 4th one
Calculate the amount of heat, in Joules, needed to raise 34.0g of water from 55.0°C to 76.0*C. The specific heat of water is 4.18 J/gºC.
Answer:
2984.52J
Explanation:
Using the formula: Q = m × c × ∆T
Where;
Q = amount of heat (in Joules)
m = mass (in grams)
c = specific heat capacity (J/g°C)
∆T = change in temperature (°C)
Based on the information provided in the question;
m = 34.0g
c = 4.18 J/gºC.
Initial temperature = 55.0°C
Final temperature = 76.0°C
Hence, Q = m × c × ∆T
Q = 34 × 4.18 × (76 - 55)
Q = 142.12 × 21
Q = 2984.52J
Therefore, 2984.52J is the amount of heat, in Joules, needed to raise 34.0g of the water.
Adaleigh is learning about renewable and non-renewable resources in her science class. She decides to take
a nature walk and makes notes of all the renewable resources that she sees. Which of the following is an
observation that Adaleigh could have made on her walk?
A. The seeds on the ground are going to grow into new trees.
B. The tallest trees had the most seeds around their bases.
C. When trees decay, they could eventually turn into coal.
D. Pine trees are older than oak trees.
Answer:
A. The seeds on the ground are going to grow into new trees.
Explanation:
Trees are renewable resources.
What is the mass of 1.00 mol of oxygen (O2)?
Answer:
Mass = 32 g
Explanation:
Given data:
Number of moles of oxygen = 1.0 mol
Mass of oxygen = ?
Solution:
Formula:
Number of moles = mass/molar mass
Molar mass of oxygen (O₂) is 32 g/mol
by putting values,
1.0 mol = mass/ 32 g/mol
Mass = 1.0 mol ×32 g/mol
Mass = 32 g
What is an nucleus ?
Nucleus is present at the centre of atom. It contains protons and neutrons. It is very small as compared to the atom.
Answer:
It is a part of a cell which controls all the activities in the cells and contains the genetic information of the cell that is to be passed down to the next cell when it reproduces.
Explanation:
It is a part of a cell which controls all the activities in the cells and contains the genetic information of the cell that is to be passed down to the next cell when it reproduces.
