47 Science questions

How many electrons are allowed in the first shell of an element?

2
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Bryony K.

1 month ago

Answered by Bryony, Science tutor with MyTutor

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Explain the structure of a gas, solid and liquid. You may include diagrams.

Gas: Free particles made from individual atomsArranged in a random order no linear formationParticles are free flowingParticles may collide occasionally due to high energyLiquid: Some atoms are attached.Arranged in some order but not linear and regularThe arrangement of particles usually repeat themselvesParticles are free to moveSolid: Regular arrangement and linear patternNot much movement other than through vibrationsA regular repetitive pattern can be identified.
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Bryony K.

1 month ago

Answered by Bryony, Science tutor with MyTutor

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Chlorine and hydrogen reach to form hydrogen chloride. What type of solution forms when this is dissolved in water?

H2 + Cl2 -> HCl(g)Type of solution: acidic
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Gina-Maria G.

1 month ago

Answered by Gina-Maria, who tutored Science with MyTutor

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What is a covalent bond?

A covalent bond occurs between two non metals. It involves two atoms sharing electrons. The electrostatic attraction is between the positive nuclei and the negative charge on the shared pair of electrons. Atoms that are covalently bonded are called molecules (usually called simple molecular structures). Covalent bonds do not conduct electricity in any state because they do not contain mobile charged particles, they have low melting and boiling points because of the weak intermolecular forces that hold covalent molecules together.
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Madeline W.

3 months ago

Answered by Madeline, Science tutor with MyTutor

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What is an ionic bond?

An ionic bond occurs between a metal and a non-metal. It is the electrostatic attraction between oppositely charged ions, where electrons are transferred to make ions. Ions that are ionically bonded are held in a giant ionic lattice. This is very strong and takes a lot of energy to overcome, therefore melting and boiling points are high. Ionic compounds only conduct electricity when molten or dissolved in water, as only in this way do they have mobile charged particles that can carry a current.
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Madeline W.

3 months ago

Answered by Madeline, Science tutor with MyTutor

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How do I balance an equation for a reaction, such as complete combustion of ethene?

Balancing equations is a simple conservation of the elements in a reaction: what you start with is what you finish with. With that in mind, let's take a look at the equation:C2H4 + O2 -> CO2 + H2OThe process for this is the same as for any equation: pick an element and count its atoms on each side. Let's start with Carbon, there are 2 in the reactants and 1 in the products. Clearly there aren't enough in the products, so we double the number of CO2 molecules produced. Note we can only increase the number of molecules involved, not individual atoms.C2H4 + O2 -> 2CO2 + H2OYou can see this changes the number of oxygen atoms in the products, but we have elemental oxygen in the reactants so we can worry about that last. There are 4 hydrogen atoms in the products and 2 in the reactants, which means we need to double the number of water molecules produced:C2H4 + O2 -> 2CO2 + 2H2ONow that carbon and oxygen are balanced, we can work out the oxygen. Note that we have 2CO2 molecules. Each molecule has 2 oxygens of its own and we have 2 molecules which gives 4 oxygens from, and then 2 more oxygen atoms from the water. Therefore we need 3 oxygen molecules and the final equation is:
C2H4 + 3O2 -> 2CO2 + 2H2O
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Kieran M.

3 months ago

Answered by Kieran, Science tutor with MyTutor

283 views

Explain how red blood cells are adapted to carry out their function?

Red blood cells transport oxygen from the lungs to all the cells in the body. To do so effectively, they have lots of adaptations: Red blood cells contain haemoglobin, which is a molecule that reversibly binds to oxygen. Red blood cells have no nucleus, so that there is more room for haemoglobin in the cell. Red blood cells have a biconcave disc-like shape (it is thinner in the middle than at the edge) which increases the surface area. Red blood cells are very flexible which means they can pass through the narrow capillaries easily.Key word is explain, so must ensure that there is a link between identifying a feature/adaptation of a red blood cell and how this feature allows them to perform a specific function more effectively.
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Francesca G.

5 months ago

Answered by Francesca, Science tutor with MyTutor

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CaCO3 + 2HCl = ?

CaCO3 is a carbonate and HCl is an acid, so the products will be a salt, water and Carbon Dioxide.Removing 2 Hydrogen atoms and an Oxygen atom for the H2O, and one carbon atom and 2 Oxygen atoms for the Carbon Dioxide for the CO2 leaves us with one Ca atom and 2 Cl atoms.Therefore the salt is CaCl2The answer is CaCl2 + H2O + CO2
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Toby G.

5 months ago

Answered by Toby, Science tutor with MyTutor

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What is mitosis and what happens during mitosis?

Mitosis is a type of cell division that occurs in diploid body cells to form two identical diploid cells. In mitosis, one original cell (called a 'parent cell') replicates to form two identical 'daughter cells', each with the same genetic material as the parent cell. The daughter cells are clones of each other and of the parent cell. There are six phases of mitosis. First there is interphase, where the DNA in a cell replicates itself to form two sets of its chromosomes. The cell spends most of its time in interphase. Next, prophase occurs, and the chromosomes in a cell condense and become visible and the nuclear membrane dissolves. After this is complete, the cell goes through metaphase, where the cell's chromosomes line up in the middle of the cell. Anaphase comes next, and this stage is where the two identical copies of each chromosome are separated to opposite ends of the cell. After anaphase comes telophase, where nuclear membranes form around the two separated groups of chromosomes. Then, during cytokinesis, the cell cleaves itself in two, resulting in the two genetically identical daughter cells. The cycle can then repeat itself.
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Joely R.

6 months ago

Answered by Joely, Science tutor with MyTutor

733 views

How does blood circulate through the heart?

De-oxygenated blood in the body returns to the right atrium of the heart through the superior and inferior vena cava. This blood is pumped through to the right ventricle, the tricuspid valves prevent any backflow of blood. The blood in the right ventricle is then pumped out into the lungs for oxygenation through the pulmonary artery. The pulmonary vein brings the blood back into the heart, into the left atrium. From there, the blood is pumped into the left ventricle (the last chamber of the heart). The left ventricular wall of the heart is very thick and powerful which aids it to pump the oxygenated blood (through the aorta) out of the heart and to the rest of the body. 
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Clarisse B.

8 months ago

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535 views

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