Yes, they do.
Alkalis feel soapy
alkalis are corrosive, normally water soluble and are very soapy.
Alkalis generally feel slippery and soapy to the touch. This sensation is due to their ability to react with oils and fats on the skin to form soap. Additionally, alkalis can be irritating and cause burns on the skin if handled improperly.
An alkali is a basic substance that reacts with an acid to form a salt. Alkalis have a pH greater than 7 and typically have a bitter taste and feel soapy or slippery. Examples of alkalis include sodium hydroxide (lye) and potassium hydroxide.
Both bases and alkalis are substances that can neutralize acids, have a bitter taste, and feel soapy to the touch. They also commonly release hydroxide ions (OH-) in water.
Alkalis typically feel slippery or soapy to the touch due to their ability to react with oils and fats on the skin to form soap. This sensation is a result of the alkaline nature of alkalis, which can disrupt the skin's natural oils and proteins. However, direct contact with alkalis can be irritating or corrosive to the skin, so it is important to handle them with care and use appropriate protective equipment.
No. Bases feel soapy. Though feeling either is not recommended.
A base has a slippery soapy feel.
All alkalis are soluble in water.
The mineral with a soapy feel is called talc. Talc has a greasy or soapy texture and is often used in powders and cosmetic products.
Bases are not called alkalis. Alkalis are a specific subset of bases that are soluble in water. All alkalis are bases, but not all bases are alkalis.
This is not universally true, but Bases tend to have a 'soapy' feel. NB: I would not recommend your plunging you hands into every bucket of base you see, however ... some can burn.