Answer:
The correct answer is b.
Explanation:
Alpha particles are fully ionized helium (4He) nucleus. These nucleus consist of two protons and two neutrons. They are positively charged (+2) due to the absence of electrons. It has the same mass as the He atom (6,64 * kg) or (4 uma), and the same charge (3,2 * C).
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The correct scientific notation form of the number 5,489.6654 using only 2 significant figures is: 5.5 * 10³
Scientific notation is a way to represent very large or very small numbers in a more concise and manageable format. It consists of two parts: a coefficient and an exponent of 10.
In your given number, 5,489.6654, we want to express it in scientific notation using only 2 significant figures. Significant figures are the digits in a number that contribute to its precision.
Identify the significant figures: From the given number, we have two significant figures, which are 5 and 4.
Determine the coefficient: To represent the number in scientific notation, we want the coefficient to be between 1 and 10. In this case, we can round the number to 5.5 (rounding the 8 up).
Determine the exponent of 10: To express the number 5.5 in scientific notation, we need to move the decimal point in the original number to the right by one place.
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Answer:
5.4 × 10^3.
Explanation:
Not 5.49 × 10^3, 5.4 × 10^7, or 5.5 × 10^3.
Light absorbed by objects, enters the eyes, and is refracted by the optic nerve in the retina.
B.
Light reflects off objects, enters the eyes, and is detected by the optic nerve in the retina.
C.
Light refracts off objects, enters the eyes, and is captured as a photograph by the lenses.
D.
Light reflects off objects, enters the eyes, and is detected by light-sensitive cells in the retina.
The human eye see objects through light reflects off objects, enters the eyes, and is detected by the optic nerve in the retina. The answer is letter B. The rest of the choices do not answer the question above.
a pure substance because it is an element.
an impure substance because it is chemically combined.
an impure substance because it is a mixture.
Answer is: a pure substance because it is a compound.
Pure substance is made of only one type of atom or only one type of molecule, it has definite and constant composition with distinct chemical properties.
Emerald (beryl) is chemical compound (beryllium aluminium cyclosilicate) with the chemical formula Be₃Al₂(SiO₃)₆. Pure beryl is colorless.
An emerald can be described as an impure substance because it is a mixture. Therefore, option D is correct.
The chemical formula for emerald is Be₃Al₂(SiO₃)₆, indicating that it is a compound composed of beryllium (Be), aluminum (Al), and silicon (Si) atoms bonded to oxygen (O) atoms.
However, emeralds can also contain impurities or trace elements such as chromium (Cr) or vanadium (V), which give them their characteristic green color.
These impurities or trace elements are present in small amounts and are incorporated into the crystal structure of the emerald.
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Yes. The NaCl will precipitate.
Yes. The BaSO4 will precipitate.
Yes. Both the NaCl and the BaSO4 will precipitate.
Yes. The BaSO₄ will precipitate in this type of double replacement reaction.
This is a type of reaction in which two reactants exchange ions to form two new compounds.
Na₂SO₄ (aq) + BaCl₂ (aq) ⇒ NaCl(aq)+ BaSO₄(s)
The precipitate which will be seen at the bottom of the reaction flask is solid BaSO₄.
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Answer: The correct answer is Yes, will precipitate.
Explanation:
Double displacement reaction is defined as the reaction in which exchange of ions takes place.
Precipitate is defined as the insoluble salt which emerges when two different solutions are mixed together. It settles down at the bottom of the flask after some time.
The chemical equation for the reaction of sodium sulfate and barium chloride follows:
Barium sulfate settles down in the reaction flask and is considered as a precipitate.
Hence, the correct answer is Yes, will precipitate.
There are 3.75 moles of oxygen in a 1.25 mol sample of CaCO₃.
Limestone is primarily a crystal form of CaCO₃ (calcium carbonate). According to its chemical formula, the molar ratio of CaCO₃ to O is 1:3. The moles of oxygen in 1.25 moles of CaCO₃ are:
There are 3.75 moles of oxygen in a 1.25 mol sample of CaCO₃.
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As the molecular formula of CaCO₃ suggested, that there are 3 moles of oxygen are there in 1 mole of CaCO₃.
So in 1.25 mol of CaCO₃ contains=1.25 ×3 moles of oxygen
=3.75 moles of oxygen
So there are 3.75 moles of oxygen are there in 1.25 mol of CaCO₃.