The properties of acids are: (A), (C) and (D).
Explanation:
Acids taste sour, and most
acids are poisonous. Furthermore, acids react with certain metals to
produce hydrogen gas. Few acids are corrosive as well. The option (B) is not valid because acids react with BASES (not with other acids) to produce salt and water. Hence A, C and D are the correct options.
Pushing a broke down car, even done by more than one person, is difficult especially if the distance to be covered is quite far. A car is heavy and it requires a lot of force to start the car moving. This is because the inertia of the car to remain at rest is great. Additionally, the force applied in pushing the car must be greater than the frictional force to cause it to accelerate. The frictional force is dependent on the mass of the object which means that the frictional force acting on the car is also great. Finally, with every push of the car, the frictional force will always be present and acting on the opposite direction. The push that will be supplied must be sustained all throughout.
Il existe troi types de rayons produits lors de la désintégration des éléments radioactifs:
-- "particules alpha" . . . noyaux d'hélium, composés chacun de 2 protons et 2 neutrons
-- "rayons bêta" ou "particules bêta" . . . flux d'électrons
-- "rayons gamma" . . . rayonnement électromagnétique avec les longueurs d'onde les plus courtes connues et l'énergie la plus élevée
